Galatians 2:21

Christ died in order that men might live before God by His grace in spite of a broken Law; if men could keep the Law of themselves and live, there would be no call for grace, and the death of Christ would be proved a useless sacrifice. διὰ νόμου. Law was never, like faith, instrumental to justification (cf. Galatians 2:16). Accordingly, Paul never speaks of justification through Law, but either ἐκ νόμου or ἐν νόμῳ. Here, as in Galatians 2:19, διὰ νόμου really denotes a legal environment, and the verse argues that if righteousness was really within men's reach under a legal dispensation, then there was no occasion for the death of Christ at all.