(died ca. 65 C.E.). Key figure in establishing Christianity as a world religion. St. Paul was born Saul of Tarsus, a Jew who persecuted the new sect known as Christians, then later converted to this religion. He played a critical role not only as an effective proselytizer, but also as a religious thinker who modified the teachings of the new sect to make them easier for the people of the Greek and Roman world to accept.