Galatians 1:14

and I advanced in the Jews' religion beyond many of mine own age among my countrymen, being more exceedingly zealous for the traditions of my fathers. [Paul's first proposition is that though it might be possible that he was taught the gospel by men, or that he might have attempted to originate it, it was certainly highly improbable; for his whole early life showed a strong antipathy and aversion to such teaching, and an intense love for that very form of teaching which was now being used to pervert the gospel. Of these very facts the Galatians themselves were in a manner witnesses; for they had doubtless heard the common report concerning them, and had also learned them from Paul himself at a time when they had no bearing on the question now discussed. Paul made no secret of his past life (1 Corinthians 15:9; 1 Timothy 1:13; Acts 22:4-5; Acts 26:10-11). Thus the story of his miraculous call, with which they were perfectly familiar, was evidently true. By "my fathers" Paul means his spiritual fathers, the Pharisees. He was zealous for the whole Jewish religion, as expounded by the Pharisees, with all its forms, rites, laws, etc., both divine and human.]