Charles Ellicott Commentary Galatians 1:23

"but they only heard say, He that once persecuted us now preacheth the faith of which he once made havoc;" — Galatians 1:23 (ASV)

Had heard.—Rather, were hearing.

The faith.—Not quite, yet, “the body of Christian doctrine,” which was in process of forming rather than already formed, but the one cardinal doctrine of faith in Christ. (Compare to Romans 1:5, and the note there.)