Annul or invalidate. Comp. Mar 7:9; 1Co 1:19; Gal 3:15.
The grace of God (τὴν χάριν τοῦ θεοῦ)
Χάρις is, primarily, that which gives joy (χαρά). Its higher, Christian meaning is based on the emphasis of freeness in a gift or favor. It is the free, spontaneous, absolute loving kindness of God toward men. Hence often in contrast with the ideas of debt, law, works, sin. Sometimes for the gift of grace, the benefaction, as 1Co 16:3; 2Co 8:6, 2Co 8:19; 1Pe 1:10, 1Pe 1:13. So here: the gracious gift of God in the offering of Christ.
Is dead (ἀπέθανεν)
More correctly, died; pointing to the historical incident.
In vain (δωρεὰν)
Groundlessly, without cause. See on 2Th 3:8. The sense here is not common. It is not found in Class., and in N.T. only Joh 15:25. In lxx, see Psalm 34:7, 19; 108:3; 118:161; 1 Samuel 19:5; Sir. 20:23; 29:6. Comp. Ignatius, Trall. v. Paul says: “I do not invalidate the grace of God in the offering of Christ, as one does who seeks to reestablish the law as a means of justification; for if righteousness comes through the law, there was no occasion for Christ to die.”
Additional Note on Gal 2:14-21.
The course of thought in Paul's address to Peter is difficult to follow. It will help to simplify it if the reader will keep it before him that the whole passage is to be interpreted in the light of Peter's false attitude - as a remonstrance against a particular state of things.
The line of remonstrance is as follows. If you, Peter, being a Jew, do not live as a Jew, but as a Gentile, as you did when you ate with Gentiles, why do you, by your example in withdrawing from Gentile tables, constrain Gentile Christians to live as Jews, observing the separative ordinances of the Jewish law? This course is plainly inconsistent.
Even you and I, born Jews, and not Gentiles - sinners - denied the obligation of these ordinances by the act of believing on Jesus Christ. In professing this faith we committed ourselves to the principle that no one can be justified by the works of the law.
But it may be said that we were in no better case by thus abandoning the law and legal righteousness, since, in the very effort to be justified through Christ, we were shown to be sinners, and therefore in the same category with the Gentiles. Does it not then follow that Christ is proved to be a minister of sin in requiring us to abandon the law as a means of justification?
No. God forbid. It is true that, in seeking to be justified in Christ, we stood revealed as sinners, for it was Christ who showed us that we could not be justified by the works of the law; that all our legal strictness only left us sinners. But the inference is false that Christ is thereby shown to be a minister of sin.
For to say that Christ is a minister of sin, is to say that I, at his bidding, became a transgressor by abandoning the law, that the law is the only true standard and medium of righteousness. If I reassert the obligation of the law after denying that obligation, I thereby assert that I transgressed in abandoning it, and that Christ, who prompted and demanded this transgression, is a minister of sin.
But this I deny. The law is not the true standard and medium of righteousness. I did not transgress in abandoning it. Christ is not a minister of sin. For it was the law itself which compelled me to abandon the law. The law crucified Christ and thereby declared him accursed. In virtue of my moral fellowship with Christ, I was (ethically) crucified with him. The act of the law forced me to break with the law. Through the law I died to the law. Thus I came under a new principle of life. I no longer live, but Christ lives in me. If I should declare that righteousness is through the law, by reasserting the obligation of the law as you, Peter, have done, I should annul the grace of God as exhibited in the death of Christ: for in that case, Christ's death would be superfluous and useless. But I do not annul the grace of God.