I am verily a man [which am] a Jew, born in Tarsus, [a city] in Cilicia, yet brought up in this city at the feet of Gamaliel, [and] taught according to the perfect manner of the law of the fathers, and was zealous toward God, as ye all are this day.
Note 2 at Ac 22:3: Paul's defense before the Jews began with him reminding them that he was every bit as much a Jew and Pharisee as any of them claimed to be. It was not as though he didn't understand their objections. Paul admitted that at one time he persecuted Christians to the point of death in his zeal for the Law (Ac 22:4).
He then recounted his miraculous conversion on the road to Damascus (Ac 22:6-16). These non-Christian Jews listened attentively throughout this account, revealing the tremendous impact that Jesus and His followers had made upon the Jewish people. The real point of contention in this instance was not whether or not Jesus was the Jewish Messiah, but rather how the crowd exploded when Paul said that the Lord was sending him to the Gentiles with the message of salvation (see note 13 at Ac 22:22).