Galatians 1:13-14. “For ye have heard of my conversation in time past in the Jews’ religion, how that beyond measure I persecuted the church of God, and wasted it: And profited in the Jews’ religion above many my equals in mine own nation, being more exceedingly zealous of the traditions of my fathers.”
This is not the only reference Paul made in his letters to the churches about his history of actively persecuting believers before he himself came to salvation. He refers to it in Acts 22:5; 26:9-11; Gal. 1:13,23; Phil. 3:6; I Tim. 1:13. He was very proud of his zealous seeking out and persecuting of believers, thinking he was protecting the Law of God that he learned in his youth.
When he speaks of his “conversation” in verse 13, he is talking about his behavior. Conversation, in the time of the King James translators, meant the way of life, the behavior. This was Paul’s major focus before his conversion. He was just as zealous about persecuting the church then as he was about establishing the church later, after he came to know Christ.
His reference to “the Jew’s religion” is simply a reference to Judasim–the following of every letter of the law. Paul loved Judaism before his conversion just as much as he loved Christianity afterward. Before, he truly believed that the only way to know God was through following not only the inspired Old Testament scriptures, but also practicing all the body of law derived from those scriptures by man. He proclaimed himself to have been a “Pharisee of the Pharisees,” observing every detail, and severely persecuting those who turned to the new Way, trusting in the death and resurrection of Jesus Christ alone for their eternal future.