Galatians 3:21

‘Is the Law then against the promises of God? God forbid. For if there had been a Law given which could make alive, truly righteousness would have been of the Law.'

Is the Law then in opposition to the promises of God? Not at all. No one will pay more reverence to the Law than Paul. There is no fault with it. It reveals sin. It is holy (Romans 7:7). Indeed had it been possible to give a Law that could give life, that is how righteousness would have been provided for us. But the trouble is that we are too sinful (Romans 7:14). All that the Law can do is mediate death to us, for, try as we might, we cannot keep the Law. Its final act, then, is to reveal to us our sinfulness and condemn us. It is not, however, the Law that is at fault, but us. Thus it fails as an instrument of salvation, not because of its weakness, but because of our weakness.