19 Why then the law? It was added because of transgressions, until the offspring should come to whom the promise had been made, and it was put in place through angels by an intermediary. 20 Now an intermediary implies more than one, but God is one.
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. 22 But the Scripture imprisoned everything under sin, so that the promise by faith in Jesus Christ might be given to those who believe.
23 Now before faith came, we were held captive under the law, imprisoned until the coming faith would be revealed. 24 So then, the law was our guardian until Christ came, in order that we might be justified by faith.
Finally, we consider the purpose and function of the law, which Calvin sums up in the following three ways:
(i) The law discloses to men the righteousness of God, and in so doing convinces them of their sin. This is the 'accusing' function of the law. Through the law man must learn that he is a sinner, before the message of the forgiveness of sins can mean anything to him.
(ii) The second office of the law is, to cause those who without constraint feel no concern for justice and rectitude, when they hear its terrible sanctions, to be at least restrained by a fear of its penalties. This is the 'civil' use of the law, and it serves the purpose of God's common grace in the world at large.
(iii) The third use of the law is that it is a rule of life for believers, reminding them of their duties and leading them in the way of life and salvation. It is 'an excellent instrument to give them from day to day a better and more certain understanding of the divine will to which they aspire, and to confirm them in the knowledge of it'.
One supremely important consideration, however, underlined by Calvin, is that the law 'no longer exercises towards us the part of a rigorous exacter, only to be satisfied by the perfect performance of every injunction'. We are no longer slaves, but sons, members of a family.