Paul raises the objection his opponents would bring. If Jews like Peter and Paul stop relying on the law and seek to be justified by Christ alone, they seem to put themselves on the level of the "sinners of the Gentiles" (Galatians 2:15). Does that make Christ the one who leads people into sin?

Among several readings, Gill suggests this may be "an objection of the adversary" to free justification, as if it "made void the law, discouraged the performance of good works, opened a door to licentiousness." Barnes frames the question this way: "Is it a fair and legitimate conclusion that this is the tendency of the gospel?" Paul asks it out loud in order to reject it.

Paul answers with his strongest denial: "God forbid" (Galatians 2:17). The real transgression, he says, would be going back: "For if I build again the things which I destroyed, I make myself a transgressor" (Galatians 2:18). Then he points to his own life: "I through the law am dead to the law, that I might live unto God. I am crucified with Christ: nevertheless I live; yet not I, but Christ liveth in me" (Galatians 2:19-20). Barnes says Paul answers by "referring in the following verses to his own case."

The word "minister" is diakonos, a servant or attendant. The question is whether Christ serves sin's interests. "God forbid" renders the Greek me genoito, literally "may it not be," Paul's sharpest way of rejecting an idea.

Paul had just set "Jews by nature" beside "sinners of the Gentiles" (Galatians 2:15). Gill gives one reading of "found sinners" as being reckoned sinners by those who still insisted on the law. Gill points to Romans 6:1, where Paul answers the same objection: "Shall we continue in sin, that grace may abound?"

Paul's answer shows that grace does not make Christ the servant of sin. The gospel does not leave people as they were. It joins them to Christ so that they live "unto God" (Galatians 2:19). Matthew Henry gives Paul's reply in plain words: "God forbid," that we should "entertain such a thought of Christ, or of his doctrine."

Barnes thinks it probable that Paul has in mind an objection "which has in all ages been brought against the doctrine of justification by faith." Paul does not answer it by adding the law back in. He answers it with a life: "the life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave himself for me" (Galatians 2:20).