By Bart D. Ehrman, The University of North Carolina, Chapel Hill
The New Testament’s ‘book of Acts’ wants to stress a major component in the spread of the Christian faith throughout the Roman world—the geographical spread of the faith. Right off the bat, the disciples follow Jesus’s instructions to preach the gospel and convert Jews in Jerusalem. Their missionary activities begin in Chapter 2, on the Day of Pentecost—a major Jewish festival, celebrated 50 days after Passover.

The Miracle of Language
It’s a bit less than two months after Jesus’s death. As was true with Passover, at Pentecost, numerous pilgrims flocked into Jerusalem for the celebration. And, so, once again, it’s a crowded place.
On this particular occasion, the disciples are gathered together in prayer, and as Jesus predicted, the Holy Spirit comes upon them with great supernatural signs. They hear the sound of a great rushing wind and see that above their heads there are tongues of flame, and they begin speaking in foreign languages.
We have pilgrims from around the world who have gathered in Jerusalem at the time, all of them speaking other languages, and the Apostles now are speaking in these other languages. They do this in languages, of course, but they don’t know, preaching the gospel, to the amazement of everyone.

When these other Jews see this great miracle, they wonder what’s going on, and Peter explains to them, “That all of this is happening because of the power of God, because Jesus, the messiah has died, and now the Holy Spirit has come upon his followers.” He tells the crowd that, “They, the Jews, killed Jesus, but now God has raised him from the dead, and so they need to repent.”
Peter converts 3,000 of them on the spot.
Record-breaking Conversion
The disciples continue from there, making more and more converts in Jerusalem, as many as 5,000 more at one time, just days later. Eventually, their success creates jealousy among the Jewish leaders, and most of the Christians are driven out of Jerusalem.
But, according to the author of Acts, God uses this persecution for good, as it allows the message then to be taken to other places. Opposition to the Christians follows them, in particular, at the hands of a highly religious Jew named Saul, who was later to be called Paul.
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The Conversion of Paul
In a miraculous event described in Chapter 9, Saul himself has a vision of Jesus while traveling on the road to the city of Damascus, where he’s off to persecute the Christians. He sees Jesus, who confronts him, and he realizes that Jesus really is the Son of God. And on the spot, Paul converts to believe in him.

Paul is commissioned by Christ to take the gospel message further afield. And most of the second half of Acts narrates his missionary journeys with Christian companions, as he takes the gospel message to other lands, making the Christian church a worldwide movement, spread throughout major urban areas of the Roman world.
The Christian Faith Reaches Rome
The narrative provides a city-by-city account of Paul’s preaching, the overall success he had, and the opposition he faced. It narrates the converts he made from one location to another. Rome itself, of course, was the capital city of the empire, and by far, its largest metropolitan area. Despite heated opposition, Paul ends up taking the gospel there, to the heart of the Roman world.
The narrative of how that happens is a bit complicated. After his final missionary journey to the lands of Asia Minor, in Greece, Paul is called by God to return to Jerusalem, to confer with the Apostles. While there, he’s arrested by the Roman authorities for creating social unrest in the Jewish community.
According to the book of Acts, Paul remains in prison for years. When it’s finally clear that he will not be able to receive a fair trial, he uses his rights as a born Roman citizen and appeals to Caesar himself for a fair trial.
The final part of the book of Acts narrates the adventures Paul experiences during his journey to Rome, and it ends with him in a Roman jail, preaching the gospel to all who would come to hear. And so, geographically, the gospel had now spread from the capital city of the Jews, Jerusalem, to the capital city of the entire Roman Empire, Rome.
Common Questions about How the Christian Faith Reached the Roman World
On that day, Jesus’s disciples had gathered in Jerusalem for prayer just like many other pilgrims. As Jesus had foretold, the Holy Spirit came upon them with supernatural signs. And the Apostles started speaking other languages that were previously foreign to them. As they preached the Christian faith, Peter explained what was happening and he converted 3,000 people on the spot.
The highly religious Jew, Saul, was a prominent opponent of the Christian faith, but as he was on his way to the city of Damascus aiming to persecute Christians, he had a vision of Jesus. Jesus confronted Saul, who realized that Jesus really was the son of God. He converted immediately and was later called Paul.
When Paul is called by God to return to Jerusalem after a missionary journey, he is arrested by the Roman authorities in Jerusalem because of creating social unrest in the Jewish community. This arrest leads to Paul being sent to prison in Rome, where he preaches the Christian faith to anyone who would hear.