Paul stands before his accusers and, addressing them in Hebrew now (22.2) begins like this:
“I am a Jew, born in Tarsus in Cilicia, but brought up in this city, educated with strictness under Gamaliel according to the law of our ancestors, and was zealous for God just as all of you are today. I persecuted this Way even to the point of death, tying up both men and women and putting them in prison, as both the high priest and the whole council of elders can testify about me. From them I also received letters to the brothers in Damascus, and I was on my way to make arrests there and bring the prisonersto Jerusalem to be punished.”
(Acts 22.3-5, NET)
Paul tells them, simply, that he is one of them (v.3a). He says that he had the best possible education in the strict manner of the law of our fathers, and that this came from Gamaliel (Acts 5.34, 9.20). His zealousness was inspiring (v.3b) and would have brought to mind the acts of Phineas in Numbers 25.1-18: simply, Paul was as straight and as strict, and as willing to do whatever was needed as they came and people knew it (v.5a).
Despite this, despite being as prepared and as driven as possible, Paul still renounced, rejected, and repented of this life when he came to know the truth about Jesus (as he explains in vv.6-21). No matter how good we (feel) we have it, when we come to know the truth about Jesus we are compelled to shed from our lives whatever is in conflict with the life of the Spirit that His presence produces in us (cf. Romans 6.1-11).