I'm Jonathan Phillips, a history professor at Royal Holloway University of London.

Join me on the journey of a lifetime, taking me 12,000 miles through 7 countries to uncover and to explore the stories of the first Christians.

In Bethlehem, I shared the celebration marking the birth of Christ.

Then, I followed in Christ's footsteps, from his childhood in Nazareth to his betrayal, his Crucifixion, and his Resurrection.

Christians believe the story of Christianity begins with Christ's Resurrection.

11 of the original disciples remain and are given a final commission by the risen Christ to spread the gospel, the Good News, to all people and all nations.

[Bell tolls] One man, above all, takes that universal call seriously.

Named Saul in Hebrew and Paul in Greek, he becomes a catalyst for a new and radical understanding of God.

His transformation is one of the most compelling in history, but it will be just the beginning of his incredible story as he makes the God of one nation into a God for all peoples.

Throughout my journey to explore early Christianity, it became clear that St. Paul held the key to the faith's survival and growth.

The Bible introduces Paul, not as an apostle, but a soul of Tarsus, a Pharisee and enemy of the church, who persecutes Christians and all that they stand for, a threat to the ancient religion of Israel.

Yet it would be that same man whose fire, passion, and sense of purpose propelled this emerging faith into the wider world, a man whose story and letters make up the majority of the New Testament.

But who was he, exactly?

I needed to know more about him.

Tourists, with good reason, flock to the stunning ruins of the Roman city of Ephesus, now in modern Turkey.

As they walk its fine streets, little do they know what a treasure lies hidden in the hills above them, a shrine to the Apostle Paul that has been concealed in a cave for centuries.

To see such a place was truly exciting.

Of course, I knew the images inside were created after his death, but this was still a huge thrill.

Well, this is an amazing moment.

We've struggled up this hillside above Ephesus and I've come face-to-face with St. Paul.

I feel quite emotional, I guess.

I've read about him for so long.

It's one of the oldest images we have of him and it is how I imagined him.

He's somebody whose glance is certainly going to hold your attention and we know he's a great speaker.

I think this is absolutely beautiful.

After Jesus, Paul did more to shape Christianity than any other man.

But, in trying to understand who he was, I had to start from the beginning.

My journey will begin where he was born, with the name Saul, in the city of Tarsus, in what is today the country of Turkey.

He grew up as part of what was known as the Great Diaspora, the spreading out of Jewish communities across the known world.

As a busy modern city, Tarsus's days as a world-renowned center for the study of rhetoric and philosophy seem long gone.

It was a place of swagger and self-confidence and its motto proclaimed "Tarsus Metropolis: first, fairest, and foremost".

It was a place Paul was proud to be from.

I came to Tarsus to get a feeling for Paul's early life.

I wanted to discover more about where he grew up and a motorbike is the best way to explore Tarsus.

In modern downtown Tarsus, archaeologists uncovered the remains of the ancient city center.

Tarsus was one of the leading cities of the Roman world and notables, such as Marc Antony and Cleopatra, chose to hold their initial meeting here during the 1st century.

St. Paul was born as a Jew and a Roman citizen, here in Tarsus, and he and his family prospered in this vibrant Roman settlement.

In the old city, I met Nadir Durgun, a municipal official and advisor on the ruin.

Is this a street that Paul, himself, would've walked down?

-An illustrious list of names, there.

Yeah.

-So Tarsus was obviously a thriving, prosperous place, then?

-Yes.

I think that's one of the key things to trying to understand Paul, is that he's a city dweller.

I mean, this man is such a profound influence on the whole development of Christianity and world history.

To actually look around, instead of think -- -When Paul was growing up, Tarsus, for all its wealth and splendor, was still a conquered territory and only the chosen few enjoyed the prestige of Roman citizenship.

Although the majority of the population today are Muslims, the city protects and maintains ancient locations that might help me to get a sense of Paul's early days.

The Well of Paul, where he drew his water, is visited by pilgrims, even today.

Popular tradition holds that its waters still have healing powers.

Lovely.

Thank you.

2nd- and 3rd-century artifacts and inscriptions found in these ruins identify this as the house where Paul grew up.

The remains of the home are preserved by a modern protective enclosure.

My next stop was the banks of the River Tarsus, perhaps a touch cleaner, in Paul's day, but now polluted by nearby industrial centers.

It's hard to believe that, in Paul's day, this was a thriving university town, like Oxford or Cambridge.

People write of the students lying around on the riverbanks, dressed in fine linen, gossiping away and debating the key issues of the day.

In an area where the faith once flourished, the only remnant of Christianity today, here in Tarsus, is this: the Church of St. Paul.

It's now a museum.

But when Paul was in Tarsus, there were no Christian services because Christianity did not yet exist.

Two of the most important Jewish groups were the Sadducees and the Pharisees.

The Sadducees were conservative, priestly aristocrats, vigorously opposed to Jesus and early Christianity and notable for the fact that they did not believe in an afterlife.

The Pharisees had a genuine concern for the holiness of God and His law, although they were criticized by Jesus for thinking that personal holiness was enough to approach God.

Saul's prosperous family sent him to Jerusalem to study under the most famous and brilliant Pharisee teacher: Gamaliel.

Do you think Paul would've ever met Jesus?

I don't think so, but I do think they were in Jerusalem at the same time because Paul's conversion is about 33; he would've been here from about 15 and Jesus was crucified in the year 30.

-In Galatians, Paul wrote...

But in Jerusalem, a new sect, first called The Way and based on the teachings of a young rabbi named Jesus, was attracting converts.

This group claimed that its founder had risen from the dead after being crucified by the Roman authorities and that He was the fulfillment of God's ancient promise to his people: that a Messiah would arrive to bring in God's new kingdom.

To Saul, this was anathema.

His reaction was to join in the persecution of Jesus's followers, even participating in their deaths.

Among them was the first Christian martyr, Stephen.

We first meet Paul -- or Saul, as he is known, at the time -- during the stoning of St. Stephen, the man who became the first Christian martyr.

The texts tell us that this happened outside the city gates and one location favored is what's now behind me: the gate known as the Damascus Gate.

So what did these first Christians believe?

They certainly believed that Jesus was the Promised One of God.

But they were also faithful Jews.

They continued to worship in the temple and to attend synagogue.

They believed the demands of the law were still valid.

But they also believed that God was doing something new and they were prepared to lose their lives for it.

This mural shows the stoning of Stephen, and his last moments on Earth.

Behind, standing approvingly, is Saul, persecutor of the Christians, watching his sworn enemy die.

Under threat of persecution, many Christians fled to the city of Damascus and Saul sought permission from the Jewish authorities to pursue them there and bring them back to Jerusalem for trial.

But it was on the Road to Damascus that one of the most extraordinary moments in the Bible took place, and its impact still reverberates today: the moment Saul the persecutor became Paul the disciple.

Luke tells the story.

-Approaching Damascus, suddenly a light from heaven flashed around him; he fell to the ground and heard a voice saying to him... -This radical sense of change, of transformation, is something that generations of Christians have experienced and can identify with.

Yet, in his Letter to the Galatians, Paul's own account is less dramatic.

He makes no mention of this famous scene.

What he certainly describes is a vision of Jesus, after which, Paul conferred with no living soul, went off to Arabia, and then came to Damascus.

Perhaps he was simply trying to digest the enormity of what had happened to him.

It must, after all, have been an overwhelming experience and, on this crucial point, at least, the texts agree.

What Paul says is he had a revelatory vision of the risen Jesus.

He claims to have had a real visionary experience and that, at that moment, this realization that the Jesus he had not believed could possibly be the Messiah turns out to have been demonstrated -- at least, in his mind, to be so -- turns him around.

-Following the narrative in the Book of Acts, the blinded Paul continued on to Damascus, where, instead of persecuting Christians, he joined their number.

There, he was healed and baptized by the community's leader: Ananias.

Saul, the persecutor, had become Paul, the apostle.

Almost immediately, Paul began to preach about Jesus in the synagogues.

The other followers of Jesus were amazed by this turnaround: the old enemy was now working with them.

Yet Paul's former Jewish colleagues were livid.

The persecutor became the persecuted and Paul had to get out of Damascus, fast.

Paul returned to Jerusalem, but not to his former life in Judaism as an establishment Pharisee.

Instead, he sought to join the fledgling Christian community, who remained unconvinced of his conversion.

He persisted in preaching to the other Jews in the synagogue until, after yet more threats against his life, it was decided that he ought to return home to Tarsus for a while.

-There are some tensions at an early stage.

Those are the kinds of -- what shall we call them?

-- family squabbles that you would normally expect when people are beginning to do these things and Paul is by no means a shy personality.

I mean, he really, firmly, believes he understands something that others do not and he'll gladly tell people when he disagrees with them and, at times, that gets him in trouble.

-But one of the Jerusalem Christians had believed Paul's conversion to be genuine.

His name was Barnabas and he sought Paul out in Tarsus.

Could you tell me what the importance of Barnabas, Paul's right-hand man, was?

I think Barnabas was his sponsor at the beginning and his educator.

I think Barnabas would've been the leader in what Luke called the first journey.

-Together, they traveled to Antioch.

Now called Antakya, in modern Turkey, Antioch was to become one of the most important cities in the story of early Christianity.

Behind me lies Antioch, in Paul's day, the third-biggest city in the Roman Empire.

It was pivotal in the spread of Christianity.

It was in Antioch that the disciples were first called Christians.

When they begin to be described as Christians is quite a controversial topic, partly because we don't know, for sure, if they described themselves as Christians or were described by others as Christians.

In the Book of Acts, for instance, in 11:26, you get the first instance where Christians are said to be described as Christians.

-We're so familiar with the word "Christian" that it's easy to forget that it was not in use straightaway for the first followers of Jesus and part of that is because they really don't see themselves as separate from Judaism, at all.

Certainly not initially.

All these early followers of Jesus really wanted to say was that God, in Jesus Christ, had brought Judaism to its promised completion.

But this was not to last.

Eventually, the tensions were too great and the followers of Jesus were thrown out of the synagogues.

The name "Christian" then became more common as the gospel spreads beyond its original Jewish base.

Probably, the word "Christianos", the word that we're translating as "Christians", is really a Latin-based term, believers being described as such in a Greco-Roman context.

Maybe some self-definition, based on an attempt to separate themselves from the mother faith, as it were, Judaism.

-Early Christians couldn't build churches, for fear of persecution.

They could meet in each other's homes or more remote locations, such as this, the natural cave known as St. Peter's Grotto.

This was one of the first Christian churches in Antioch, but today, Christians can only worship here on special occasions.

I did hear about one remaining Catholic church that still holds regular Sunday masses.

Although the church keeps a low profile, my taxi driver thinks he knows where it is.

The Catholic church of Antioch has been allowed to operate, since 1852, with the blessings of the Muslim authorities.

The church's priest, Father Domenico Bertogli, explained Antioch's importance to early Christianity.

The early followers and believers of the Jesus movement still called it The Way.

In Antioch, all that would change in the year 44 AD.

After 20 years as a priest here, Father Bertogli says he will continue to minister to the 1,000 Christians still living in Antioch.

Paul and Barnabas spent a year in Antioch, preaching with early Christian leaders and prophets.

Eventually, they resolved to set out across the empire and begin spreading the Christian message.

Paul's journey took him through much of Asia Minor, now called Turkey.

Using Antioch as a base, he traveled the Mediterranean region, preaching the Word of Christianity.

His first journey began here, at the port of Samandag, just southwest of Antioch, and his destination was the island of Cyprus.

Paul preached across Cyprus before sailing on to Perga on the Turkish coast.

In Paul's day, the best way to move long distances was by sea.

You could manage perhaps 80 or 100 miles a day, far, far quicker than you'd move on land.

There were, of course, some problems: reefs were uncharted, piracy was a frequent occurrence; by far, the greatest trouble was from storms and Paul, himself, was shipwrecked no fewer than 3 times as he strove to spread the Christian Word.

From Perga, he would travel north to Pisidian Antioch.

2,000 years ago, this isolated valley held a thriving community.

All that remains now are these spectacular remnants of another era.

It was here, in Pisidian Antioch, that Paul and Barnabas made the momentous decision to turn their focus from the Jews to the Gentiles.

St. Paul was nothing, if not courageous.

For the first of his missionary journeys, he plunged into the heart of Asia Minor, to this place, Pisidian Antioch, in the Roman province of Galatia.

His first target was the Jewish community, based in the synagogue, which now lies underneath the remains of St. Paul's Basilica, behind me.

Paul also preached to the Gentiles and this divided the Jews.

Those who were not converted became very suspicious of his intentions.

His mission to the Gentiles is very much a deliberate extension of, not only Judaism, more generally, but his absolute belief that this is God's calling for him to bring the Gentiles into Judaism at the end of the age.

Paul's sermon in the synagogue was a dramatic success and, soon, the whole town wanted to hear him.

The Jews became jealous of this attention and began to harass him.

Paul responded sharply that God had commissioned him to preach to all.

Furious, the Jews began to move to drive him out and Paul contemptuously shook the dust from his shoes, stalked off to Iconium, to continue his mission there.

Even with the superb Roman road system, travel, in Paul's day, was incredibly hard: the danger of attack from wild animals or robbers, plus sheer debilitating exhaustion from repeated exposure to cold rain or the searing Mediterranean sun.

After leaving the cool, rolling hills of Pisidian Antioch, Paul journeyed through a harsh mountainous landscape to a very different place: the city of Iconium, now known as Konya, a vast, sprawling metropolis on a wide, open plain.

Just like in Pisidian Antioch, Paul's eloquence won him many admirers, but provoked antagonism from the Jews.

He was forced to flee.

Paul was facing ever-increasing danger.

He'd been forced to leave Pisidian Antioch, but here, in Iconium, he was badly beaten, shackled in irons, and cast into prison.

Paul's journeys during these years became the subject of many later Christian legends.

One of the most famous of these is set in this very town of Iconium.

According to the story, while Paul was preaching in Iconium, his words caught the attention of a young noblewoman about to be married.

Her name was Thecla.

-Thecla heard him preaching from the window where she was, according to one text, fixed like a spider's web, and she heard him preaching about abstinence and salvation and she decided to leave her fiancé and follow Paul on his missionary journeys.

Thecla's mother was horrified at this slight to the family's honor and demanded that her daughter be burnt at the stake.

-She is tied to a pyre, which is lit on fire, in the city of Iconium, in the amphitheater, and all the people of the city are shouting for her execution.

In the middle of the execution, a rainstorm comes and wipes out the fire, miraculously.

-From Iconium, Thecla came to this place, Pisidian Antioch.

Almost immediately, she was set upon by a powerful local nobleman who tried to force himself upon her.

Quite naturally, she rebuffed him, but, enraged, the man resolved to punish her and have her killed in public, in this theater, in front of thousands of spectators.

[Growl] -In one case, one of the female lionesses actually defends Thecla against the other lions and the other animals.

In an act of desperation, she throws herself into a pool of water that has ravenous seals.

This is considered to be, in the text, her self-baptism and, at that point, a bolt of lightning strikes the water and kills the seals, leaving her unharmed.

The governor of Antioch is so amazed at this miracle that he allows her to go free, not wanting to incur the wrath of God.

PHILLIPS: Thecla was said to have gone to live in Syria for many years, but even then, she was not safe.

At the age of 90, Thecla was assaulted by jealous pagans, but a fissure opened in the solid rock and she vanished forever in the chasm.

-While there's no evidence for Thecla's existence in the New Testament itself, in the letters written by Paul or the texts written immediately about Paul after his death, there is evidence, from the 2nd century, that suggests that she was an extremely popular saint even by the middle of that century, so, while the legend does not give us any basis for which to assert her authenticity as a historical person, she had an enormous impact on the early church.

PHILLIPS: Some Christian writers describe Thecla as an apostle; others, as the first female martyr.

The details of her life and death may, indeed, be fictitious, but the very fact that stories circulated of a Christian woman teaching, performing miracles, and following an ascetic religious life is extremely significant.

The ancient world was patriarchal, dominated by men, and there are very few stories of religious women in Greek and Roman paganism.

Christianity offered some women new roles, a new way to achieve fame.

Thecla was a model for such women and she became a saint whose shrines have been visited by pilgrims for centuries.

Paul and Barnabas continued their journey through Asia Minor, towards the cities of Lystra and Derbe, where a very different encounter took place.

In Lystra, Paul healed a man who had never walked, since birth.

In Acts, Luke tells us: "Paul called to him in a loud voice, 'Stand up!'

And the man jumped to his feet and started walking."

The pagan onlookers were amazed and believed Paul and Barnabas to be the Greek gods Zeus and Hermes.

To the bewilderment and dismay of Paul and Barnabas, the priest of Zeus brought oxen and garlands and prepared to sacrifice the animals to them.

What the priest got in return for his pains was a sermon on the true nature of God...

Here was a new source of conflict.

Alongside opposition from Judaism, Paul's message had to deal with challenges from Greek and pagan theologies.

Meanwhile, back in Jerusalem, trouble was brewing for Paul.

Word had reached the Jewish-Christian leadership that Paul was preaching a version of Christianity that appeared to deny some important aspects of Jewish law.

But soon, Paul would face more immediate danger.

[Shouting] Although badly injured, Paul survived.

Barnabas took him to the nearby town of Derbe to recover.

After his near-death experience, Paul was confronted by hostile visitors from Jerusalem.

Paul faced judgment before the Jewish-Christian apostles.

He needed their approval to continue his missionary work and he knew the odds were against him because his accusers would also be his judges.

Paul's future would be at stake, but even more importantly, the fate of Christianity itself would hang in the balance.

He left for Jerusalem with a heavy heart.

Here in Jerusalem, the apostles Peter, James, and John carried on as the leaders of the church after the Crucifixion and Resurrection of their Lord.

They were still not entirely convinced about Paul.

After all, he was one of those who had persecuted them and had been an onlooker at the stoning of Stephen.

-Other than Paul and, of course, Peter, the two sort of big names that you hear about, the third important figure in the first generation of the Jesus movement is James, himself.

He really does become the leader of the early Jesus followers in Jerusalem, within a period of maybe 5 to 10 years after the death of Jesus.

-But we mustn't forget Peter, the disciple to whom Jesus had entrusted the leadership of the church.

He was a faithful Jew who realized that God was doing something new.

-Peter has a very important role to play as the preeminent example of Jesus's disciples.

He also plays a very important role in the spread of Christianity from Jerusalem and the Judean environs out into the larger world.

-But there is more to Peter.

Called to be a leader, he has to change the way he thinks and the way in which this happens, according to the Book of Acts, is through a vision he has just before meeting a Gentile centurion: Cornelius.

Cornelius is a Gentile who's quite favorably disposed to Jewish things, seems to be interested in Judaism, but isn't a Jew and Peter has a vision.

He sees a sheet coming down with various animals within it, most of which would've been prohibited by Jews to eat.

In the vision, Peter is told that he can go ahead and rise and eat these things, as a way of indicating that he can line up with the Gentiles and have fellowship with the Gentiles, so it's a way of breaking down barriers between Jews and Christians and Peter becomes instrumental, in the life of the Jerusalem church, to beginning to break down those barriers and pave the way for how Christianity will embrace Gentile peoples.

PHILLIPS: So the way is being paved for some kind of showdown: Paul, on one side, convinced that God is calling out to Gentiles as well as Jews; James and the Jerusalem church on the other, equally convinced that this new movement is for Jews, alone; and, somewhere in the middle, stands Peter.

-Here, we've got Paul, who's, you know, gone off, now, to the Gentile cities and is trying, really, to expand in that environment.

James tends to be associated with Jerusalem and, in most ways, he tends to be identified with a much more traditionally Jewish form of the Jesus movement.

Peter, in some respects, stands in between the two and so we have these different sort of positions for these early figures.

The dominant question at the Council of Jerusalem was this: "Could people become full followers of Christ if they did not adopt the strict customs demanded by Judaism?"

Paul is the person who wants to admit Gentiles, non-Jews, into the life of the community straightaway.

Not only that, but he basically says all the marks of belonging, like circumcision and other things, have no place here.

-Jewish identity centered on following over 600 laws and 5 Books of Moses.

These ranged from the Ten Commandments to obscure dietary laws and observant Jews were expected to know and to obey all of them.

For James, you could have the law and Christ.

For Paul, obedience to the law was completely irrelevant.

-Eventually, the position that results is the one associated with the views of Paul: namely, that Gentiles need no longer be circumcised, in order to be a part of this movement.

But that's something that they really are going to debate for decades -- actually, generations -- before they really resolve it thoroughly in all of Christianity.

This was a powerful debate with potentially far-reaching consequences.

Had the conclusions reached been different, Christianity could simply have remained a minor sect of Judaism.

But, in the end, under the authority of James, the more open approach was taken: Paul was free to continue to preach to the Gentiles.

It was a great victory for Paul and a great victory for Christianity.

Now, with the blessing of the Jerusalem apostles, Paul, joined by his old friend and mentor Barnabas, set out for Southeast Turkey, to launch his second missionary journey.

Once again, I find myself in Turkey, where I will start the second leg of my journey by retracing Paul's return to his base in Antioch, today, called Antakya.

Paul's purpose in Antioch was to organize his second missionary journey and to bring early Gentile Christians already living there the various edicts laid down by the Council of Jerusalem... To abstain from eating the meat of animals that has been sacrificed to pagan idols, to abstain from eating meat that has not been thoroughly drained of blood, to abstain from the meat of animals strangled or carrion left by predators, or the remains of animals killed accidentally.

To abstain from any act of sexual immorality.

Even in these straightforward decrees, one sees the long hand of the Jerusalem church seeking to keep Jewish influence alive in what were overwhelmingly Gentile communities.

Paul's influence stretched only so far.

Paul's story again took me to one of the first Christian churches in Antioch: St. Peter's Grotto.

This is one of the few places of Christian worship to survive in Antioch.

It's quite something to let your imagination wander and to conjure up a picture of Paul praying in this church.

But tensions still existed between Gentile and Jewish Christians.

When Peter visited Paul in Antioch, he refused to eat with the Gentile converts, a direct insult to Paul.

Even Paul's ally Barnabas sided with Peter and he, too, would not eat with Gentiles.

Feeling betrayed, Paul parted company with Barnabas.

But perhaps there was more to their falling out.

-The reason, I think, they split was that Paul insisted on emphasizing the Crucifixion, that is, the way Christ died; whereas, for Barnabas and everyone else, the primitive kerygma, it's just the fact He died for us.

For Paul, the way He died showed the extent of the love of Christ and he wasn't going to let anyone forget that.

I think, without Paul, we wouldn't have a Passion narrative in the gospels.

-[Singing] He would've just died and then, all stress would be on the Resurrection and Ascension.

It was 400 years before the cross was used as a symbol; a further 100 years before a figure was put on the cross; 600 years before a realistic figure was put on the cross, a suffering figure, you see?

So Paul really stands out from the whole of the New Testament in his stress on the modality of the way Christ died.

-The more I follow in Paul's footsteps, the greater admiration I have for his endurance.

I can imagine the apostle and his companions walking thousands of miles along roads such as this one, just north of Tarsus, a route that he took on his second missionary journey.

By now, Paul had been joined by Silas for his second missionary journey.

They began by revisiting the churches in Derbe and Lystra.

But it was in the road to Iconium and Pisidian Antioch that Paul had another vision, a direct call to leave the work in Asia Minor and to concentrate his efforts elsewhere.

Paul traveled to Troas and, while there, he had to decide whether to end his journey or continue on to Europe.

A further vision appeared to answer his question, with a call to go to Macedonia to preach.

In the company of a physician named Luke, Paul set sail for what is now modern Greece.

Luke would later write the account of the early years of Christianity that has come down to us as the Acts of the Apostles, as well as the gospel that bears his own name.

Paul landed in the Greek city of Neapolis, where he set foot on European soil for the first time.

Neapolis means "new city" in Greek.

Under the Roman Empire, it was a prosperous seaport.

I'm wondering what Paul must've felt as he stepped ashore here, at Neapolis in Northern Greece.

His voyage had taken him from one continent to another, from Asia to Europe.

It was a daunting prospect, an ambitious prospect, and, in some ways, a risky one, too, yet, it transformed the opportunities open to him.

Father Pavlos is priest of the Holy Metropolis of Philippi, Neapolis, Thassos, and Kavala.

Why do you think he came to Neapolis, in particular?

-[Speaking Greek] INTERPRETER: We know Philippi, at these times, was a very important colony and Paul chose to arrive here, in this strategic place, in this important city of Macedonia because this would be the place where Paul will meet Europe and Europe will meet Christianity.

This meeting will change the course of history and, from this point, everything will be completely different.

PHILLIPS: Paul's next stop was Philippi, 12 miles inland.

I had read of Philippi's history in my studies, but I wasn't prepared for the magnificent ruins that still radiate the power and the greatness of the Roman Empire.

This, in Philippi, is a stretch of an old Roman road, the Via Egnatia.

Originally, it ran 700 miles, from the Adriatic Sea to the Aegean Sea.

It was built to allow Roman armies swift transit across the empire, but, to Paul and his companions, roads such as this were vital arteries as they sought to spread the Christian Word.

When Paul came to Philippi, he chose this beautiful, peaceful location about a mile outside town to begin his preaching.

From his audience of a group of women stepped forward Lydia, a seller of purple cloth.

Paul brought her to this river and Lydia holds the distinction of being the first recorded baptism in Europe.

The sight of Lydia's baptism is marked today by a chapel which includes a popular baptistry.

-[Speaking Greek] Father Eleftherios is in charge of Lydia's baptistry.

[Speaking Greek] INTERPRETER: It was not a coincidence that Lydia was among the women by the river.

She was a merchant, selling porphyra, a kind of dye that was used to color precious textiles, at the time.

As Luke wrote, "God opened the eyes of Lydia's heart in order to understand Apostle Paul's message."

PHILLIPS: Starting with Lydia, these waters have transformed believers for almost 2,000 years.

ELEFTHERIOS: Alleluia, alleluia, alleluia.

-Ritual immersion has been a purification rite in Judaism and for earlier civilizations, but, for Christianity, baptism took on a whole new meaning and significance.

What is baptism?

The word means "to dip into".

So if you're baptized, you're dipped into water to purify you, to wash away your sin.

But for Paul, baptism was more.

Baptism was a rite that united you with Jesus Christ, and not just once, but in perpetuity.

It was, therefore, a deeply serious matter.

The images used by Paul to describe this are startling.

In the same way that Jesus died a physical death, so, in baptism, the convert dies a spiritual death as the waters close over them.

As Paul puts it, the convert is united with Christ in both His death and His Resurrection.

A new life begins, meant to be lived with the utmost moral seriousness.

As Jesus has lived and died, so the same obligation is placed upon the follower of Jesus.

At the same time, we must remember that ancient society, like Paul's, had a much greater sense of everyone belonging together.

Of course individuals mattered, but society mattered more.

So, if a head of a household was baptized, then, more often than not, the rest of his family would follow suit.

Time and again, in Acts, we read of individuals and families being baptized on the same occasion, and this is what happens with Lydia.

For many Christians, baptism symbolizes a deepening of their relationship with Jesus.

[Speaking Greek] INTERPRETER: Lydia was baptized here and, immediately after the baptism, she kindly asked Paul and his company, Silas, Luke, and Timothy, to visit her house.

That night, Lydia's family and relatives were baptized and became Christians.

With this simple and quiet way, Lydia's relatives created the first church, the first home church, in Philippi.

Before leaving Philippi, Paul encountered a slave woman who, he believed, was possessed because she was able to tell fortunes, an ability which earned money for her masters.

Paul was utterly fed up with this.

He snapped "In the name of Jesus Christ, I order you to come out of her."

The slave girl's owners were furious at this treatment of their property.

They had Paul and Silas dragged before the magistrate here in the forum.

Without ceremony, the men were whipped, beaten, and sent to prison.

According to tradition, Paul and Silas were chained in this prison.

As Paul and Silas knelt in prayer, a providential earthquake struck the town and the prison door fell open.

The jailer was terrified his captors were going to flee, but Paul, showing a stubborn streak, refused to move until the magistrate came to apologize for the earlier beating.

Paul was, after all, a Roman citizen.

According to Acts, the authorities reported these words to the magistrates and they were afraid when they heard that Paul and his companion were Roman citizens, so they came and apologized to them and asked them to leave the city.

Paul left Philippi for Thessaloniki, but Luke stayed behind.

Thessaloniki is now the second-largest city in Greece, a hub for international commerce.

In Paul's day, it was home to many prosperous merchants because it was a major seaport that also straddled a key overland trading route: the Via Egnatia.

Many of Thessaloniki's merchants sold their wares here, in what was once the busy market district.

With dozens of stores packed side-by-side, today, it looks like the ruins of an ancient shopping center.

In Philippi, Paul had enjoyed the support of the wealthy Lydia but, here in Thessaloniki, he had no such patron.

He writes of having to work night and day at his trade of tentmaking just to make ends meet, yet his preaching went well.

His message of the humble Messiah struck a chord with many of the people here, and a great multitude of the Greeks were won over.

In Thessaloniki, Paul was a houseguest of a man named Jason.

While staying there, Paul was converting Greek Gentiles, but he was also preaching the kingdom of God to Greek Jews, and many were converted.

As usual, Paul's success provoked opposition from some in the Jewish community.

They brought his associates before the local magistrate and accused the Christians of promoting the interests of their own king above that of the emperor.

The men managed to post bail, but this was a bad sign.

Once again, things had become too hot and Paul and Silas had to slip away from here.

Although Paul had to make a hasty exit, the first Christian community in Thessaloniki had been established and Paul didn't leave it to fend for itself.

Even though he couldn't be there in person, he could to support it through writing.

Paul's two Letters to the Thessalonians are the first of these and, like all his later letters, they were written in response to a particular question or problem.

In this case, the question was this: "If the Lord is returning soon, as he promised, what is the point of thinking too far ahead about the future?

Why, for example, carry on working?"

Paul's answer is to say "Yes, we believe that Jesus is returning soon, but that's no excuse for inaction.

Instead, you must live your lives with hope and as if He were here already.

That means you don't give up living a good life."

And, to reinforce the idea, he uses an image familiar to his Greek audience in Thessaloniki: Jesus's return will be his parousia, a Greek word that means "entrance", used to describe the entrance of the emperor as he made a triumphant entry into his city.

"So, Jesus Christ's return will be just as glorious, but it may take time; be patient."

From Thessaloniki, Paul came 50 miles southwest here, to Berea.

His message was well-received, and numerous men and women, particularly, from the Greek community, became believers.

This altar frames the synagogue stairs where Paul stood and preached to the people of Berea.

Can I ask you what you think the special features of Paul's personality were, his character?

-[Speaking Greek] INTERPRETER: He was not scared of deprivation or persecutions and, in every place he would go, he would teach the gospel, believing in his heart that everything he was saying was true, and that made the people believe.

-This rare period of peace was not to last.

Paul's enemies in Thessaloniki tracked him down and he was forced out.

In our next episode... Paul continues on to Athens, the largest city in Greece, where he will have one of his most famous encounters.

In the course of his missionary journeys, his life would take many twists and turns that would ultimately find him back in Rome and in mortal danger.

With his enemies in the holy city vowing to kill him, Paul's only escape would be into the custody of the Romans.

And, in Rome itself, Paul would confront his fate, persecuted by one of the most cruel tyrants in history.

I'm Jonathan Phillips.

Join me next time, as we continue our journey on The Road from Christ to Constantine.