Why did Saul of Tarsus become a persecutor?

Answer 1

Saul, a devout Jew and Pharisee (the Jewish sect best characterized by their pursuit of "religious correctness"), was of the opinion that Jesus was just another false Messiah, like others who had come along before Him (see Acts 5:36-39).

As harsh as Saul's persecution was, he carried it out with all good conscience (Acts 23:1), fully believing that he was doing God's will. In his own words:

Acts 22:3-5 - "I am indeed a Jew, born in Tarsus of Cilicia, but brought up in this city at the feet of Gamaliel, taught according to the strictness of our fathers' law, and was zealous toward God as you all are today. I persecuted this Way to the death, binding and delivering into prisons both men and women, as also the high priest bears me witness, and all the council of the elders, from whom I also received letters to the brethren, and went to Damascus to bring in chains even those who were there to Jerusalem to be punished."

Acts 26:9-11 - "Indeed, I myself thought I must do many things contrary to the name of Jesus of Nazareth. This I also did in Jerusalem, and many of the saints I shut up in prison, having received authority from the chief priests; and when they were put to death, I cast my vote against them. And I punished them often in every synagogue and compelled them to blaspheme; and being exceedingly enraged against them, I persecuted them even to foreign cities."

Following his conversion, Paul expressed profound regret for the damage he had once done to the church, and worked all the harder toward its benefit (1 Corinthians 15:9, 10).

[Quotes from NKJV]