I am a Pharisee, the son of a Pharisee: for the hope of the resurrection of the dead am I called in question — So he was in effect; although not formally, or explicitly.
Related Commentaries of Acts 23:6
Acts 23:6
6 But when Paul perceived that the one part were Sadducees, and the other Pharisees, he cried out in the council, Men and brethren, I am a Pharisee, the son of a Pharisee: of the hope and resurrection of the dead I am called in question.