Acts 9:20

He proclaimed Jesus (ekhrussen ton Ihsoun). Imperfect indicative, inchoative, began to preach. Jesus, not Christ, is the correct text here. He did this first preaching in the Jewish synagogues, a habit of his life when possible, and following the example of Jesus. That he is the Son of God (oti outo estin o uio tou qeou). This is Paul's platform as a Christian preacher, one that he always occupied to the very end. It was a complete reversal of his previous position. Jesus had turned him completely around. It is the conclusion that Saul now drew from the vision of the Risen Christ and the message through Ananias. By "the Son of God" Saul means the Messiah of promise and hope, the Messianic sense of the Baptist ( John 1:34 ) and of Nathanael ( John 1:49 ) for Saul is now proclaiming his faith in Jesus in the very synagogues where he had meant to arrest those who professed their faith in him. Peter laid emphasis on the Resurrection of Jesus as a glorious fact and proclaimed Jesus as Lord and Christ. Paul boldly calls Jesus the Son of God with full acknowledgment of his deity from the very start. Thomas had come to this place slowly ( John 20:28 ). Saul begins with this truth and never leaves it. With this faith he can shake the world. There is no power in any other preaching.