Who were the Church that Paul persecuted according to this teaching?
The Church Paul persecuted was the assembly of God, specifically the Jewish believers of Christ's earthly ministry after His ascension, located at Jerusalem. These were the believers over whom Peter was preaching in the book of Acts, as mentioned in Galatians.
Les explains that Paul is writing in Galatians 1:13-14 about his past in the Jews' religion. The Church he persecuted was the assembly of God, which context identifies as the Jewish believers of Christ's earthly ministry after He had gone back to glory. They were in Jerusalem, and Peter was preaching to them in the book of Acts. Paul says he persecuted them beyond measure and wasted it. Les notes this was after Christ's ascension, not during His earthly ministry, and that Judaism had become watered down with man-made laws and traditions.
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:
More Questions
What did Paul say about his persecution of the church in Galatians 1:13?
In Galatians 1:13 Paul said his past lifestyle in the Jews' religion included persecuting the church of God beyond measure and wasting it.