"But while the unrighteousness and condemnation of all are attested by the law, it does not follow (if we make the proper use of it) that we are immediately to give up all hope and rush headlong on despair. No doubt, it has some such effect upon the reprobate, but this is owing to their obstinacy. With the children of God the effect is different. The Apostle testifies that the law pronounces its sentence of condemnation in order “that every mouth may be stopped, and all the world may become guilty before God” (Rom 3:19). In another place, however, the same Apostle declares, that “God has concluded them all in unbelief;” not that he might destroy all, or allow all to perish, but that “he might have mercy upon all” (Rom 11:32:) in other words, that divesting themselves of an absurd opinion of their own virtue, they may perceive how they are wholly dependent on the hand of God; that feeling how naked and destitute they are, they may take refuge in his mercy, rely upon it, and cover themselves up entirely with it; renouncing all righteousness and merit, and clinging to mercy alone, as offered in Christ to all who long and look for it in true faith. In the precepts of the law, God is seen as the rewarder only of perfect righteousness (a righteousness of which all are destitute), and, on the other hand, as the stern avenger of wickedness. But in Christ his countenance beams forth full of grace and gentleness towards poor unworthy sinners."
- John Calvin, Institutes of the Christian Religion, Book II.8
Note how one of the purposes of God's Law is to testify to our guilt and deserved condemnation before the absolutely Holy God. But this knowledge should not lead us to "give up all hope and rush headlong on despair." Instead, recognizing that the Law is just and true, and that we are guilty and helpless, we may find a reason to cling to Christ. Because now the cross and empty tomb make more sense to us, since it is there that Jesus paid the penalty of the Law for us, making us free.
The Law shuts mouths, so that nobody can justify themselves before God who knows all things. It forces us by its divine authority to accept a guilty verdict. But this is so that we may obtain mercy if we repent and confess our sins to God now. We may obtain mercy and find grace through faith, because Jesus Christ provides our righteousness, apart from works of the Law, as a gift which we depend fully on Him for, and not ourselves.
So next time you are tempted to despair from the high standard set by God's Law, look to Jesus. And if you do not have a high enough regard for God's Law yet, let it shut you up and show you just how much you really do need mercy.
Χάρις και ειρήνη
Grace and peace