21 Is the law then against the promises of God? God forbid: for if there had been a law given which could have given life, verily righteousness should have been by the law.
English Standard Version
21 Is the law then contrary to the promises of God? Certainly not! For if a law had been given that could give life, then righteousness would indeed be by the law.
21 If such is the case, is the law, then, an anti-promise, a negation of God's will for us? Not at all. Its purpose was to make obvious to everyone that we are, in ourselves, out of right relationship with God, and therefore to show us the futility of devising some religious system for getting by our own efforts what we can only get by waiting in faith for God to complete his promise. For if any kind of rule-keeping had power to create life in us, we would certainly have gotten it by this time.
New King James Version
21 Is the law then against the promises of God? Certainly not! For if there had been a law given which could have given life, truly righteousness would have been by the law.
New Living Translation
21 Is there a conflict, then, between God's law and God's promises? Absolutely not! If the law could give us new life, we could be made right with God by obeying it.
If that promise was enough for salvation, wherefore then serveth the law? The Israelites, though chosen to be God's peculiar people, were sinners as well as others. The law was not intended to discover a way of justification, different from that made known by the promise, but to lead men to see their need of the promise, by showing the sinfulness of sin, and to point to Christ, through whom alone they could be pardoned and justified. The promise was given by God himself; the law was given by the ministry of angels, and the hand of a mediator, even Moses. Hence the law could not be designed to set aside the promise. A mediator, as the very term signifies, is a friend that comes between two parties, and is not to act merely with and for one of them. The great design of the law was, that the promise by faith of Jesus Christ, might be given to those that believe; that, being convinced of their guilt, and the insufficiency of the law to effect a righteousness for them, they might be persuaded to believe on Christ, and so obtain the benefit of the promise. And it is not possible that the holy, just, and good law of God, the standard of duty to all, should be contrary to the gospel of Christ. It tends every way to promote it.