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

When my studies took me into the world of early Christians, I realized that little captivated my imagination like their struggle to bring a fragile new faith to the world.

I embarked upon a 12,000-mile journey that would take me through seven countries and across four centuries to discover how a small Jewish sect persevered and evolved to become Christianity.

We followed the incredible journeys of the apostle Paul from persecutor of Christians to become, after Jesus, the most important man in its history.

We traveled with him as he established Christian communities in Asia Minor and then to northern Greece, where he founded the first churches in Europe.

Yet his successes made him enemies, and he was repeatedly forced to move on.

Paul's next stop will be Athens, the most famous city in Greece, where he turns adversity into opportunity in one of the New Testament's most fascinating stories.

From Athens we'll follow Paul's triumphs and tribulations in Greece and the Near East as he risks his life to build the foundations of Christianity.

His final journey will take him to Rome, where he'll go before one of the cruelest of all Roman emperors, who will hold Paul's life in his hands.

After founding the first Christian churches in Europe, the apostle Paul traveled 200 miles southwards to see for the first time the grandeur of Athens.

When he reached Athens, Paul met a breathtaking sight.

It had been the greatest city of the ancient world.

It was full of shrines and sanctuaries, dominated then, as now, by the Parthenon, the Temple of Athena.

Athens had been the cradle of civilization, the birthplace of democracy and home of some of the greatest ever authors, poets, playwrights, and philosophers, men such as Plato, Aristotle, and Socrates.

With a history such as this, Athens posed a formidable challenge to Paul.

Athens was a bastion of paganism, with literally dozens of temples crowding the city.

In fact, according to a popular saying from Paul's time, it was easier to find a god in Athens than a man.

GWYNN: A god of thunder, Zeus, as the Greeks called him, Jupiter, as the Romans called him.

A god of the sun.

A god of an open door and a god of a closed door.

And they were different gods.

Gods of small plants, of small streams, and a god of the ocean.

And all of these myriad gods and goddesses you had to keep happy.

PHILLIPS: This was the Agora, a place of trade, chatter, and intellectual sparring -- in other words, the ideal place for Paul to start his preaching.

Local philosophers began to dispute with him.

While they found his message of Jesus and the Resurrection a little strange, there was something in his words that intrigued them.

PHILLIPS: Paul wandered through Athens absorbing the rich culture and observing everything the city had to offer.

He was especially interested in the city's temples, and one in particular caught his eye.

In Athens, Paul had seen an altar inscribed with the words, "To an unknown god."

He used this as an opportunity to explain Christianity.

Here on the marble outcropping called Mars Hill, Paul addressed some of the most learned men of Greece.

As we learn from the Book of Acts, Paul's sermon about the unknown god is one of his most famous and convincing speeches.

PHILLIPS: Paul saw the profusion of temples and gods not as an obstacle, but as a sign of religious hunger.

He was keen as ever to engage in debate.

He spoke of Jesus, a man raised from the dead.

But on this point he lost his audience.

The Athenians believed in the survival of the soul and not the body.

They mocked him.

"We'll listen to you again another time on this matter," they said.

In other words, "Don't call us.

We'll call you."

Paul's work in Athens had convinced a few people -- men and women -- and the seeds of a Christian community were planted.

Retracing Paul's footsteps, I departed from Athens.

My destination was Corinth.

During Paul's time, Corinth was surpassing Athens in both size and political importance.

This is ancient Corinth, a far cry from conservative Athens, an energetic, entrepreneurial place, a boom town, a melting pot -- in many respects, a bare canvas for Paul to work from.

Paul realized that he couldn't do everything, and he wanted situations which would multiply his efforts, so that his first real missionary center was Corinth, which was one of the hubs of the ancient world.

There were travelers coming in and out, going in all directions.

PHILLIPS: In the year 49, the Jews were expelled from Rome, and many went to Corinth.

In Corinth and other congregations, the early Christians often spoke in tongues, expressing faith in unknown forms.

SALISBURY: According to the Bible, it starts with the apostles when they gathered after Christ had gone, and they had this Pentecost, when the spirits came upon them and they spoke in tongues.

And that became the mark, for them, of the reality of the phenomenon, the reality of the presence of the Holy Spirit.

And, in fact, when St. Paul goes and starts talking to communities and founding other churches, he starts worrying about people counting too much on this phenomenon, various forms of ecstasy, whether it's passing out or prophesying or something.

And he says, "Well, you know, that's not all there is."

You have to have love, you have to have the community, you have to join together in this community of the faithful.

And so there you could see the tension between ecstatic expressions and community of the faithful.

PHILLIPS: The experiences of the Jews in Rome made them more receptive to new ideas such as Paul's.

In Corinth, Paul's message reached people from all backgrounds and all levels of society.

This is an inscription in the theater at Corinth.

It says that Erastus, a Roman official, had paid for this pavement.

I'm intrigued by this because this Erastus could be the same man mentioned by Paul as the city treasurer and as an associate of his.

This was important.

Paul had decided he needed to target men of means and status who could offer support and meeting places for his new recruits.

Paul's success in Corinth continued for most of the 18 months he spent there.

As Paul became established in Corinth, he won over more and more converts, pagans and Jews alike.

The latter group, however, began to fight back.

They accused Paul of trying to persuade people to worship contrary to the law.

They had him dragged to trial here at the Great Platform, but the presiding Roman official threw the case out.

He said, "It's simply a matter of internal Jewish feuding."

We can find language that is polemical between followers of Jesus and other Jews, say, in the Gospel of Matthew.

The woes against the Pharisees that we get in Matthew 23 is a particularly poignant example, because it's actually arguments between two groups of Jews -- over Jesus, perhaps, but argument between two groups that are firmly committed to Judaism itself.

PHILLIPS: When Paul left Corinth, his destination was Antioch.

But to sail there, he first had to travel by road to Cenchreae, eight miles away.

In Paul's day, this was part of an enormous trading complex that brought together merchants from Europe and the Middle East.

It was an ideal hub for this leg of his missionary work.

While in Cenchreae, Paul fulfilled ritual vows, including having his hair cut short.

His acts of piety helped him attract followers, including a female deacon who would lead his church in Cenchreae.

One of the inhabitants of Cenchreae was a woman named Phoebe.

She was praised as a faithful servant of the church, and she offered help to many, including Paul himself.

She was just part of the vital network of volunteers so crucial in establishing early Christianity.

Paul in many ways is seen as a controversial figure, particularly his attitude towards women.

O'CONNOR: Well, I think he has been badly interpreted.

And I think Paul accepted women as fully equal and just one of the models of running a church.

You see, Paul offers four models -- a church run by a man, Gaius; a church run by a woman, Phoebe of Cenchreae; a church run by a couple, Prisca and Aquila; and a church run by a committee, the three who ran the church in Colossae.

But women for him were accepted fully as equal.

PHILLIPS: The help that Phoebe gave Paul may have included material support, much as Lydia had provided earlier.

Paul's second missionary journey had been a great success.

He had founded many new churches and converted countless Gentiles and Jews to Christianity.

When Paul returned to Antioch, he again met with his followers in his primitive cave church.

From his home base in Antioch, Paul preached throughout the area.

What it took a long time to sink in was the need for maintenance.

Paul believed that he could found churches and then leave them to the Holy Spirit.

PHILLIPS: During this period, Paul had lost touch with his churches in Asia Minor.

Paul clearly understood that without guidance his congregations might lose their way.

Although he was able to address some issues through his letters, he realized that he could better assess and resolve problems in person, so he set out on his third missionary journey.

O'CONNOR: Then Paul settled in Ephesus.

Ephesus was right in the middle of all the churches he had already founded.

PHILLIPS: Right, so he's very clever and very careful in picking the locations that he chooses to base himself.

WEDDLE: Ephesus was the capital of the province of Asia, what is basically now western Turkey.

It was one of the largest cities in the empire, after Rome and Alexandria, and it was a bustling port city with people coming in all the time from all over the ancient world.

PHILLIPS: Known as the light of Asia, Ephesus dominated the western coast of Turkey.

It was one of the four most important cities in the Roman Empire, with a population of over 250,000 people.

And its main street, the Arcadian Way, was over 100 feet wide and paved with marble.

And I'd like to show you, Jonathan, some of the rare books that we were very fortunate to purchase, and one was a gift, a very valuable gift, but these are two of the oldest books about Ephesus.

And this one in particular is the Falkner on Ephesus and the Temple of Diana.

It shows the city of Ephesus as it once was.

PHILLIPS: Why do you think Paul spent so long here?

Well, he saw it important for his mission because it was such an enormous city, and you have to remember, Paul was a very well-educated man.

He was a great rhetorician, he spoke dynamically, convincingly, and he felt here there was something in the atmosphere here.

The people were searching.

I mean, I would say the stratum of society that would have been not the lower classes but on the fringes of society were discontent.

So he sensed that, and he saw it was ready.

PHILLIPS: In this magnificent city, Artemis was the patron goddess of Ephesus.

The pagans believed that anything disrupting the worship of Artemis would threaten the city's prosperity and well-being.

WEDDLE: She was a huntress goddess, so she was connected to the wild, and she was also a virgin goddess and had associations with fertility through that, and she was a very popular Greek goddess, but this particular Artemis that was worshipped in Ephesus is shown like an eastern or Egyptian deity, standing very straight in long robes.

The most interesting and eye-catching aspect is that she seems to be covered in breasts, and this is probably a reference to the fertility aspect of her cult, a cult that a lot of people were devoted to, and we find these images of Artemis of Ephesus all over the ancient world.

PHILLIPS: This single timeworn column is all that remains of the Temple of Artemis at Ephesus.

Once a magnificent marble building longer than a modern football field, it was one of the seven wonders of the ancient world and a place of religious devotion long before the time of St. Paul.

WEDDLE: The temple itself was really a sight to behold and drew tourists from all over the ancient world, but many of them would come during annual festivals in honor of the goddess Artemis.

CRISLER: There was a wonderful wooden image of her which was brown from the fires of sacrifice and all that, the smoke, you know.

And the reason she was made of wood was because she was carried once a year on her birthday down the Sacred Way, over through the upper gate, the Magnesia Gate, and down the Embelos and the Curetès street and out past Celsus Library.

PHILLIPS: You've got Paul standing there watching the procession of this local goddess, this pagan goddess, symbol of fertility, hunting, being taken past him.

CRISLER: Yes, exactly.

PHILLIPS: I wonder what emotions that brought up in him.

CRISLER: Oh, I think with Paul, I think he was so convinced of his mission, you know, it was fuel for the fire within him, to denounce the pagan worship of this image when he was trying so hard to preach.

PHILLIPS: Paul earned a living in Ephesus as a tentmaker.

He worked from a little store here in the agora, or marketplace.

Because of the intense midday sun, the merchants sold their wares first thing in the morning or late in the afternoon.

For Paul, of course, chatting away with his customers was a superb way to meet people and to draw them in to his cause.

After almost three years of preaching, Paul had converted so many pagans to Christianity that it had started to impact upon the local economy and, in particular, the silversmiths.

As Paul's teachings began to take effect, people stopped buying statues of Artemis made by local silversmiths.

Their leader, Demetrius, began to stir up a torrent of anger against the apostle.

The furious local craftsmen poured into this great theater, and a full-blown riot ensued.

CRISLER: Demetrius had his silversmith guild down there near the harbor, and he just went along Acadian Way and gathered up the people, the populace, and they all went up into the theater, and they're screaming for two hours.

They chant all day, "Great is Artemis of the Ephesians, Great is Artemis of the Ephesians!"

And some people would like to see this as the fact that they were really religiously dedicated to Artemis, but probably the fact was that they made their living from making these little silver statues of Artemis of Ephesus, and if Paul were to convert many Christians who would then stop worshipping her, they would be out of business.

PHILLIPS: The violent pagan opposition to Paul's Christian message in Ephesus was too great, and he had to flee.

But, once more, he did leave behind enough converts to create a small Christian community.

PHILLIPS: Paul's third missionary journey differed from the first two because he didn't found any new churches.

His purpose was to strengthen his existing churches, but also to seek donations to help feed the poor Christians in Jerusalem.

Jerusalem was severely overcrowded and impoverished by heavy Roman taxation.

It was also afflicted by chronic food shortages.

It was the poor, among them the Jerusalem Christians, who were suffering the most.

Paul's efforts to feed the poor in Jerusalem, known as the Jerusalem collection, drew help from virtually all of his new churches.

One of Christianity's fundamental starting principles, and one of its truly great, monumental contributions to the modern world is the idea of charity, the idea of welfare, that you look after other people because those other people have value, and if you can give them aid, you should.

PHILLIPS: In Troas, Paul met up with his friend Luke, who would go on to play a major role, not just in the Jerusalem collection, but in the building of Christianity as we know it.

Luke was a prominent physician who held respect from the wealthy community of Philippi.

Because the church in Philippi was one of the most prosperous, Luke presented Paul with large donations from Lydia and her wealthy friends.

It was Luke who chronicled Paul's entire story in the Acts of the Apostles, and many scholars believe it was the same Luke who wrote the Gospel that bears his name.

Both of these works are among the longest and most important books of the New Testament.

Luke became Paul's traveling companion for the remainder of his third missionary journey.

In the coastal city of Miletus, Paul bid farewell to the church leaders of Ephesus and then embarked on a journey across the sea.

After ports of call in Tyre and Ptolemais, Paul landed in Caesarea, the final stop before his last journey to Jerusalem.

WHITE: He's going to go back to Jerusalem, and he's going to deliver these, these bags of money, this contribution from his Gentile converts, to James and the leaders in Jerusalem.

And that, it seems to me, says something very important about what is Paul's real understanding, because this represents a kind of symbolic gift of the Gentiles to Jerusalem.

It's a gift of, it's a gift of the Gentiles for Zion, you see, and so that, I think, suggests that we're still operating more within a Jewish frame of understanding what this movement is about.

PHILLIPS: These ruins are what remains of Herod's luxurious palace, where Roman procurators, including Pontius Pilate and Antonius Felix, wielded their power.

Caesarea became the area's most popular city.

Its port made it a strategic and economic center, protected by a 200-foot seawall, now submerged beneath the Mediterranean.

Caesarea was also prominent in early Christian history.

Here, under Peter, the Roman centurion Cornelius became the first Gentile to embrace Christianity.

During his travels, Paul heard rumors that if he went to Jerusalem he would be persecuted.

Nevertheless, he decided to return to the Holy City, in part to deliver much-needed funds to the church there.

He landed here at the port of Caesarea, but at the house of Philip the Deacon, he was told directly that if he went to Jerusalem, he would be captured by the Jews and given over to the hands of the Gentiles.

Yet Paul would not be dissuaded.

He said he was ready to die at Jerusalem in the name of the Lord.

Paul would again enter Jerusalem, home to his enemies, and come face-to-face with the people and powers who sought to destroy him.

Paul counted on his generous donation to create good will in Jerusalem, and he hoped it would ensure that he'd be well received.

But in spite of Paul's gifts, Philip the Deacon's warning would prove prophetic.

When Paul and Luke arrived in Jerusalem, they met with James and the other Christian elders.

Paul told them about his success in converting Gentiles to Christianity.

But James said he'd heard that Paul was turning Jewish converts away from the law.

James pointed out that, unlike Paul, he had been bringing a great many Jews to Christ without leaving Judaism.

Who would you characterize as his main rival?

O'CONNOR: I think his main rival would have been James, because James was a both/and person, whereas Paul was either/or.

For James, you could have the law and Christ.

For Paul, you didn't need two saviors, so that if you confessed that Jesus was the Messiah, then you were in fact condemning the law as out of date.

PHILLIPS: Paul quickly ran into trouble, and a crowd of hostile Jews began to beat him.

They cried out... PHILLIPS: The crowd dragged Paul out of the temple and began to assault him violently.

The Roman commander led his soldiers to the scene of the riot.

When the mob saw the drawn swords, they stopped beating Paul.

While the soldiers bound Paul with chains, the commander asked him what he'd done.

Meanwhile the angry crowd shouted out accusations against him.

The commander ordered Paul to be interrogated, but when Paul said he was a Roman citizen, the commander became frightened and turned him over to the Jewish high priests.

Imprisoned, Paul learned that 40 Jews had taken an oath to kill him.

He was sent to Caesarea under heavy guard but soon faced accusations of crimes against Judaism before the Roman procurator Antonius Felix.

PHILLIPS: Paul responded that he had only gone to Jerusalem to bring alms and offerings and that he was even purified in the Temple.

Paul was placed under house arrest here in Caesarea for two years.

Imagine what a frustrating experience that must have been for a man of his boundless energy.

Towards the end of this time he feared judgment and imprisonment at the hands of the authorities in Jerusalem.

To avoid this, he invoked his right as a Roman citizen to be judged by the emperor, a significant moment, as he turned his back on his Jewish past.

There was to be one more set-piece hearing, this time before the grandson of Herod the Great.

Paul passionately outlined his beliefs, and he insisted he had done nothing to wrong the Jews or the Romans.

The king was so impressed he said he almost converted on the spot, but the Romans insisted -- he had appealed to Rome, and to Rome he must go.

After two years as a prisoner in Caesarea, Paul's voyage to Rome aboard an Egyptian grain ship began.

But as Paul sailed towards Italy, the weather worsened dramatically.

Halfway through the voyage, the skies turned dark, and the winds blew violently.

The powerful storm pushed the ship to the island of Malta, where it was wrecked.

The 274 passengers, half of them prisoners, made it to shore by either swimming or floating on pieces of wreckage.

Miraculously, there was no loss of life.

"Paul had gathered a bundle of brushwood "and was putting it on the fire, when a viper, "driven out by the heat, fastened itself on his hand.

"When the natives saw the creature hanging from his hand, "they said to one another, 'This man must be a murderer; "'though he has escaped from the sea, "'justice has not allowed him to live.'

"He, however, shook off the creature into the fire and suffered no harm."

PHILLIPS: Paul stayed in Malta for three months, where he is still held in huge veneration today for the miracles he performed.

Once the west winds began to blow again, Paul could continue his journey, and he landed in Puteoli, 150 miles from Rome.

PHILLIPS: This road is called the Appian Way.

Paul himself came along here when he was brought to Rome as a prisoner around the year 61.

The Book of Acts tells us that many people came to see the famous man.

We also learn that the apostle was fortified by the strong Christian presence here.

I was wondering what Rome would have looked like when Paul arrived there.

Well, it was one of the largest cities in the world, certainly the largest in the western part of the world.

It was a very bustling metropolis.

There were people who had come to try to make their fortune in Rome.

It was very cosmopolitan.

There was a lot of entertainment -- theater, gladiatorial games.

There was constant building going on.

In fact, the first century was a time of great expansion of the empire, especially under Augustus, who was emperor at the time of Christ.

And it was said that Augustus found Rome a city of brick and turned it into a city of marble.

It became this opulent, very stunning city, and it was the center of the world.

PHILLIPS: As Seneca, a philosopher and statesman, said about Rome at the time, "The entire human race has flocked here, a city offering rich returns for both virtues and vices."

Seneca was also a tutor and adviser to Nero, who became emperor at the age of 17.

The Rome that Paul would enter was controlled by Emperor Nero, who by this time had been in power for a decade.

For a period, the empire enjoyed sound government.

Nero improved public order, and he applied himself rigorously to his judicial duties.

In character, Nero was a strange mix of paradoxes -- artistic, weak, brutal, extravagant, and sadistic.

By the year 62, Nero's reign would change completely.

After murdering his mother in a political plot, Nero's life became a series of excesses in games, music, orgies, and murder.

By the time Paul arrived in Rome, Nero was almost certainly deranged.

[ Bell ringing ] In Rome, Paul would be meeting one of the most important Christians of the age.

Recognized as the Prince of the Apostles, Peter was an early member of Jesus' inner circle, and he played a key role in bringing the message of Christ to the Gentiles.

Paul would eventually be targeted by the Romans as an enemy of the state.

I went in search of the notorious Mamertine Prison.

In Nero's day it held political prisoners, who now included Peter and Paul.

I met Father Caesar Atuire, who heads the Opera Romana Pellegrinaggi.

So tradition holds that Peter and Paul were actually detained in this prison, because it's the most likely place in Rome to detain people who were enemies of the Roman Empire.

And basically the people who were detained here were kind of thrown in down beneath us, where there's water coming up from the ground, and anyone who entered into prison here was deemed to die, basically.

It was like a death row.

This was a dark place, extremely humid.

It was always flooded beneath, and the idea of throwing these people into the water was just like canceling them totally out of humanity and basically just writing them off.

The Christians were considered as enemies of Rome because they did not abide with the religious observances of the time.

PHILLIPS: Peter, one of the original twelve apostles, had been laboring in Rome to establish a Christian community there.

As the church in Rome grew in numbers, so did the persecutions.

Fearing for his life, Peter decided to leave the city, but he would soon have his mind changed.

Today there's a small church called "Quo Vadis" that means, "Where are you going?"

Tradition holds that this marks the spot where Peter met his destiny.

The apocryphal Acts of Peter tell us that the apostle decided to flee Rome in the face of persecution.

As he left the city, he encountered Christ.

Shocked, he asked, "Domine, quo vadis?"

"Lord, where are you going?"

Christ replied, "I go into Rome to be crucified again."

Duly chastened, Peter turned around and went back inside the city.

What this tradition really represents, I think, is a manifestation of Christ's presence in Rome and Peter's determination to face martyrdom.

By the year 64, Nero's tyranny and extravagance had escalated.

Becoming ever more powerful, he ruled with an iron fist.

This area was home to the first and largest stadium in ancient Rome.

Called the Circus Maximus, it was a third of a mile long and could hold up to 150,000 spectators.

It was used for chariot races.

It was in the southeast corner of the stadium that the great fire of Rome broke out on the night of the 18th of July in the year 64.

It was a monumental blaze.

It lasted for nine days and engulfed over two-thirds of the city.

But for one group in particular, the consequences would prove even more disastrous.

Some believe that Nero was the architect behind the fire, and now he had a perfect excuse to persecute Christians with a vengeance.

ATUIRE: When Rome was burned down, the general sort of opinion was that the Christians have contributed to the destruction of this city, and it was there that St. Peter was actually detained as an enemy of the... of the empire, and for that matter he was thrown into this prison.

What happened with St. Peter is that when he was detained here, and this is like, I mean, a legend from tradition -- we do not have any scientific proof about this -- was that he used that same water to baptize the people who were actually his jailers, and for that matter he transformed the meaning of that water, which was condemnation to death, into a symbol of redemption.

PHILLIPS: Could you describe the final days of Peter's life?

ATUIRE: Well, we can only imagine, looking at this place, and then, you know, what we know from history as well.

After having been detained here for a short period of time, Peter was then taken out of this prison and taken out of the city walls to be crucified, because, remember, the crucifixions used to be carried out outside the walls, generally.

He was dragged from the hole.

The Roman legionaries, the Roman soldiers, would pull out the person and basically just push him along.

What we do know -- I mean, we do not have data about Peter's journey from this prison, but we do have data regarding other people who were condemned.

Sometimes they were paraded along and humiliated publicly before they were eventually crucified.

And we could suppose that something similar might have happened to St. Peter.

PHILLIPS: Peter the Apostle was crucified on Vatican Hill.

Feeling unworthy to be crucified like his Savior, Jesus Christ, he requested to be crucified upside down.

Peter's remains were buried on Vatican Hill.

Excavations have unearthed his probable tomb.

His relics are now enshrined in the high altar of the magnificent St. Peter's Basilica, located in what is now the Vatican.

For the next two years, Paul, as a Roman citizen, was allowed house arrest, guarded by a live-in soldier.

Paul welcomed all who came to him and tried to explain to Jewish leaders about Jesus from both the law of Moses and the prophets.

Some were convinced by what he said, but others refused to believe.

The Book of Acts ends before Paul's final days, but tradition says he was eventually moved here, outside the city walls, to this place.

It was in this holding cell that a later writer takes on Paul's voice in his last letter to Timothy.

"I am already being poured out as a libation..." PHILLIPS: Abbot Don Giacomo Brière is head of the Three Fountains Monastery in Rome.

Could you tell me about that church there which has a prison?

BRIèRE: Yes... PHILLIPS: So that's the practice of the time.

BRIèRE: It seems.

PHILLIPS: You sort of subdue somebody, effectively, by half drowning them.

BRIèRE: Yes.

PHILLIPS: And then you execute them.

After walking thousands of miles through Judea, Asia Minor, and Macedonia, this pathway is popularly said to be where Paul took his last steps before death.

Convicted Roman citizens, whatever their faith, were usually accorded the privilege of beheading, a far quicker death than the more gruesome forms of execution inflicted upon many Christians.

Popular tradition holds that St. Paul was beheaded at this pillar, and when his severed head bounced along the ground, these three fountains sprang forth.

O'CONNOR: According to the tradition, he died in the last quarter of the year 67, and because he was a Roman citizen, it was a clean death by the sword.

See, the magistrate should have given him the chance to run.

This was standard practice.

But the Emperor Nero had established the mere fact of being a Christian meant that you were worthy of death.

He had fought the good fight, he had kept the faith, and he wouldn't have wanted to die in any other way.

PHILLIPS: It was Paul who penned a doctrine that would spread Christianity beyond its Jewish roots, transforming it into a faith open to all.

As he wrote in his Letter to the Galatians, "There is neither Jew nor Gentile, "neither slave nor free, "nor is there male and female; for you are all one in Christ Jesus."

Just over a mile from Rome lies the Basilica of St. Paul Outside the Walls, the site of the Apostle's tomb.

In the 320s, the Emperor Constantine ordered the construction of a fairly modest church here, but within a few decades, a much more lavish building would emerge.

And that is the basis for the magnificent structure you see behind me today.

In the thousands of miles I've traveled, I've come to think of Paul as a man of energy and movement, so it's a little disconcerting to find the end of his journey here at his tomb.

It goes without saying that the legacy of this passionate, inspirational, controversial man has cascaded down the centuries, impacting upon Christianity and beyond.

To each generation comes the chance to interpret, or reinterpret, his life for themselves.

In Jerusalem, James would also meet his fate.

A Christian chronicler of the 2nd century, Hegesippus, writes that the Jewish scribes and Pharisees came to James for help in putting down Christian beliefs.

PHILLIPS: They wanted him to stand at the Temple and denounce Jesus and persuade everyone to do so.

But James refused.

Angered, they threw him down from the Temple and stoned him.

James knelt and prayed to God to forgive them.

One of the priests began to cry out, "Stop!

What are you doing?

This just man is praying for us."

But one among them hit James on the head with a club and killed him.

Apostle James the Just was a pillar of the early church.

True to his conviction, he stayed in Jerusalem all his life, his purpose to bring the message of Christ to the Jewish people.

And his commitment to this purpose cost him his life.

In spite of this persecution, by the end of the first century the church had managed to expand at an extraordinary rate.

Even in the Book of Acts, Luke's account of this expansion seems, at first glance, to explain this by a chain of improbabilities.

For these first Christians, faith was required to see God at work.

No other reasoning was possible.

Human intentions were subordinate to that sense of all-prevailing providence.

About a century later, around the year 180, the Greek pagan writer Celsus commented, in a somewhat barbed fashion, that it was the close-knit structure of the early Christians that provided their source of strength.

But Celsus put this down, not to something internal to the faith, but to the fact of persecution.

PHILLIPS: It's true that Christianity created opposition and that this may well have contributed to its cohesion.

But it was more than a sense of rejection that spurred on the early Christians.

Celsus would have known that it was fear of arrest that led Christians to gather in secret.

And we must also remember that the first churches were in private houses.

Only as congregations grew did also the buildings they worshipped in.

In some parts of the ancient world, persecution, as it sometimes does now, actually appears to have had the opposite effect to driving an idea underground.

Due to Paul's extraordinary work in spreading the Gospel, we find occasional moments, later in the second century, of Christians in Asia Minor taking to the streets in protest when the local governor began persecuting them.

This was a movement that appeared destined to endure, regardless.

It was confident that God was at work and that nothing could, therefore, stand in its way.

As Paul himself wrote to the first Christians in Rome, that ultimate center of persecution...

This mosaic of Christ with St. Peter and St. Paul in the Church of Santa Costanza in Rome, reminds its audience that two of the most important founders of Christianity lived and died in this city.

This fact was integral to Rome's claim to a position of preeminence in the early Christian church.

For the early Christians, the deaths of Peter and Paul represented the end of an era.

Their deep conviction and unshakable belief that Jesus is the Messiah led to many of their deaths.

As for the original apostles, with the exception of Judas Iscariot, who took his own life, they too paid the ultimate price of martyrdom.

And their deaths have been portrayed in art and literature down the centuries.

Of the original twelve, tradition holds that only one apostle, John, escaped the executioner.

John was forced into exile on the remote island of Patmos in the Aegean Sea by Roman Emperor Domitian.

There he would be confined for 11 years until his death.

In our next episode, the city of Jerusalem will be rocked by war.

We follow the terrible events of the Jewish revolt, and we see how this affected the fragile growth of the Christian faith.

We'll travel to Patmos Island and explore the cave where tradition tells us that John, exiled there, would have a striking effect on the future of Christianity.

While there, he or a namesake heard the voice of the Lord and wrote down the apocalyptic account of the end times, a work that became the final and most enigmatic book of the New Testament, Revelation.

Then we'll see the crucial battle where powerful heretics claiming special knowledge of Jesus threatened to distort, to divide, and even to destroy the Christian faith.

I'm Jonathan Phillips.

Join me next time as we continue our journey on the road from Christ to Constantine.