Saul of Tarsus, later renamed "Paul" , was a Jew who identified himself as a Pharisee. He first appears on the scene in the Bible as a persecutor of early Christians in the book of Acts, chapter 7. He was present at the stoning of Stephen. While on his way to Damascus to ferret out and punish more Christians, he had a life-changing vision in which Jesus appeared to him and blinded him. He went to Damascus where after 3 days, the scales fell off his eyes and he was converted. He spends some time with Christians and several years later, sets out on his first missionary journey. He is known as the apostle to the Gentiles.
Up until this time, the Jews were God's only chosen people, called out by God and separated from other peoples. Although the coming of Messiah had been predicted for centuries, when Jesus came and claimed to be the Messiah of the Jews, the Jews rejected his claim. They persecuted him for what they believed was blasphemy, claiming to be God. Jesus taught that God was a triune being consisting of Father, Son and Spirit. Throughout their history, the Jews believed that God was one, and they did not understand this theology, so naturally they did not accept Jesus as God.
After Jesus was crucified, his apostles were told to go out and preach the gospel to all nations, baptising people in his name. Paul, therefore, was converted after Jesus had already ascended to heaven after the resurrection. While Paul was in Damascus, he had a vision where Jesus not only spoke to him, but also showed him heaven. After this, Paul became convinced of the truth that Jesus was teaching, and was a gung-ho apostle for the gospel of Jesus. He traveled all over the Middle East converting people and growing "the church of Jesus Christ" in the first century, and it was during this time that Jesus' teachings became a separate spiritual tradition.
