Galatians / Question
Paul recalls that he “persecuted the church of God violently” and tried to destroy it. He also says he was advancing in Judaism, showing the contrast with his later calling (Galatians 1:13–14).
In Galatians 1:13–14, Paul points to what the Galatians already “heard” about him: his earlier life inside Judaism. He highlights two features of that past. First, he aggressively targeted the community of Jesus-followers, trying to damage it severely. These lines come inside Paul’s opening defense of where his message came from. Just before, he says his message is not something he received from people or learned by ordinary means, but came through a revelation of Jesus (Galatians 1:11–12).
Paul uses his well-known past as evidence in his defense. The explicit claims are straightforward: he formerly lived “in Judaism” (Judaism), he went after the Jesus-following communities with extreme intensity, and he tried to do them serious harm.
A careful answer keeps the immediate passage, the book's argument, and the whole-Bible storyline together, so the question is answered in context instead of as a detached idea.
Start with Galatians 1:13-14, then read the surrounding section so the answer stays connected to the passage's flow.
13For you have heard of my way of living in time past in the Jews` religion, how that beyond measure I persecuted the assembly of God, and ravaged it.
14I advanced in the Jews` religion beyond many of my own age among my countrymen, being more exceedingly zealous for the traditions of my fathers.