St. Paul of Tarsus (originally Saul of Tarsus) is considered by many Christianss to be the most important disciple of Jesus, and next to Jesus the most important figure in the development of Christianity.
Paul is recognized by many Christians as a Saint. Paul did much to advance Christianity among the gentiles, and is considered one of the primary sources of early Church doctrine. Some argue that it was he who first truly made Christianity a new religion, rather than a sect of Judaism.
Paul described himself as an Israelite of the tribe of Benjamin and a Pharisee (Rom. 11:1, Phil. 3:5). According to Acts 22:3, he was born in Tarsus of Cilicia and studied in Jerusalem under Gamaliel. Paul stated that he persecuted the first Christians (Phil. 3:5; cf. Acts 22:4-5) but abandoned this after having a vision of Jesus as he was on the road to Damascus, and was thereafter appointed to be an apostle of Jesus.
According to his epistle to the Galatians, Paul first went to Arabia and then spent three years in Damascus. After this period he travelled to Jerusalem where he met James the Just, the brother of Jesus (not to be confused with James the Great, son of Zebedee, brother of John).
He then began the first of his three apostolic travels through Syria, Cilicia, Turkey, Cyprus, Crete and Greece. He preached Jesus Christ to be the crucified and risen Son of God to Jews in synagogues and to the 'Gentiles' in villages and cities. He started churches wherever converts could gather to study the Jewish scriptures and in Ephesus on the Turkish west coast he even stayed two years to teach and strengthen the new Christians (according to the book of Acts chapter 19). In Athens he gave his legendary speech in Areios Pagos where in order to convert the Greeks he said he was talking in the name of the Unknown God who was already worshiped there.
Paul usually chose one or more companions for his travels. Barnabas, Silas, Titus, Timothy and John Mark were part of his team. Titus he left at Crete to help strengthen the new church there. Paul was not only a theological scholar but also a tentmaker, by which he earned his money. He organised the raising of money for victims of a famine in Palestine (details?).
Paul was persecuted many times. He suffered detention in Philippi, was lashed and stoned several times and almost murdered once. He caused a great uproar in the theatre in Ephesus, where local silversmiths feared loss of income due to Paul's activities. Their income relied on the sale of silver statues of the goddess Artemis, whom they worshipped.
Paul wrote many letters to Christian churches and to some individuals. Some of those letters (with internal evidence of Paul's authorship) have been preserved and are part of the New Testament canon. His possible authorship of the letter to the Hebrews is a question of debate. The letters he wrote from captivity are called the 'prison-letters', and were probably written in Rome.
Epistles of Paul included into the New Testament canon:
Needing work, he became a police officer under the authority of the Sadducee High Priest, and was assigned to persecute dissidents against Rome. This caused internal conflict. While traveling to Damascus on a clandestine mission to arrest Nazarenes, his psychological crisis peaked. His revelation was thus actually a resolution of his divided self. He fused the mystery religions, Judaism and the Jerusalem Church into an entirely new belief and centered it on the figure of Jesus.
The rest of his life was spent codifying the new faith. However, the Jerusalem Church members were devout Jews and did not hold with his beliefs. To strengthen his stand, he invented his own account of events of his life and claimed an early dispute and later agreement with the Jerusalem Church.
Maccoby, Hyam (1986). The Mythmaker: Paul and the Invention of Christianity. San Francisco: HarperSanFrancisco.