Paul the Apostle, previously known as Saul of Tarsus and now often called St Paul (2BC–67), was a Messianic Jewish-Roman writer and rabbi. He was a convert to Christianity. It is believed that he wrote thirteen books of the Bible, together called the Pauline epistles. They are letters to churches and Christians. He wrote these letters to encourage them, to help them understand Christian teaching, and to help them to live Christian lives.