2:21 purge himself from these. That is, we should not be influenced by the “vessels unto dishonour” in the church. In fact, depending on the particulars in a given case, such members may need to be brought under church discipline and even excommunicated.
2:21 prepared unto every good work. Compare II Timothy 3:17. If we would be “prepared unto every good work,” we must study, believe and heed the Holy Scriptures.