Expositor's Bible Commentary Commentary Galatians 2:18

"For if I build up again those things which I destroyed, I prove myself a transgressor." — Galatians 2:18 (ASV)

The interpretation of this verse is not difficult in the light of the interpretation of v.17 given above. The legalizers had accused Paul of encouraging sin because his doctrine overthrows the law for God’s grace. This Paul denied. Nevertheless, he replies, sin could be encouraged if having once come to God by faith in Jesus Christ the one coming should then return to law as a basis for the relationship. This is an argument e contrario. It refers to a situation precisely like that one into which Peter had fallen—he turned back to Jewish practices and ended up sinning against the Gentiles. In view of the following verses, Paul is likely thinking of the great sinfulness of turning from the Savior (whom the law anticipated) to mere ordinances (for a similar argument, see Heb 6:4-6).