Saul was a Jewish man who converted to Christianity near the very beginning of the new religion. After he converted, he took the Christian name Paul. In the 30s and 40s AD, soon after Jesus was crucified, Paul travelled all over preaching Christianity. He went to Greece and to what’s now Turkey and to Damascus in Syria. A new thing that Paul did was to preach to people who were not Jews. Paul told people that Jesus wanted them to be good – they should never tell lies, or steal, or cheat anyone in a trade. But Paul said that love was more important than any of these things (I Corinthians). Paul also told people that Jesus didn’t want anybody who got divorced to remarry. A man could only have one wife, and a woman could only have one husband. And he said that women should obey their husbands, and not speak in public. Jesus hadn’t really told people how to live: he was more concerned that the world was about to end. He told people how to get to heaven. Paul was organizing a community of Christians, and he told people how to live as Christians.
Thanks to Paul’s preaching, and the preaching of other apostles, a lot more people became Christians. By the time of the Roman Emperor Claudius, in the 40s AD, there may even have been Christians in Rome. The Roman historian Suetonius (writing about 100 AD) said that “Claudius threw out of Rome the Jews who were always making a fuss in the name of Chrestus.” Suetonius means a time about 15 years after Jesus was crucified (but he was writing written about 85 years later).
Around the same time, about 50 AD, tradition tells us that Roman officials killed both Paul and the apostle Peter in Rome for being Christians. Nobody is sure if this is true, or exactly what the charge was. Being a Christian was not actually illegal until around the reign of the Roman Emperor Trajan, about 100 AD. But maybe they were killed for disturbing the peace, or just for public preaching.
Learn by doing: write and preach a sermon yourself
Nero and the Great Fire in Rome