If he was doing this at the time of Elijah, this would have slit his throat for straddling the issue between HaShem and Baal. (I Kings 18:21) If you ask me, Paul first got in touch with the Apostles of Jesus in Jerusalem when he returned from Damascus, applied to join the Sect of the Nazarenes and was rejected on the basis that he was a persecutor of the Nazarenes. So, he was set loose, and caused a havoc in Jerusalem, preaching that Jesus was the Messiah, son of God and that he had resurrected. (Acts 9:20; 26; II Timothy 2:8) The idea that Jesus was the Messiah was not a matter of being recognized by Paul but fabricated, if focus on II Timothy 2:8) That was the last straw. The Jewish authorities got on their heels to arrest him for preaching idolatry in Jerusalem but, afraid that he could involve the Apostles, these took Paul down to Tiberias, and from there, they sent him back to Tarsus where he belonged. About being a Christian, became is not the word, Paul founded Christianity in the city of Antioch after a whole year that he, at the invitation of Barnabas spent a whole year in the Nazarene synagogue of Antioch. At the end of that year, the disciples started being called Christians for the first time. Not the disciples of Jesus but the members of the Synagogue who had converted from the Gentiles. (Acts 11:26)