Chapters 6-11 of Book II of Calvin’s Institutes give us his treatment of the law and the gospel. Crucially, the law and the gospel are not set against each other, as if the law (of Moses) was given simply to tell us the bad news that we can’t earn our way to God, leaving us with no hope until we encounter the good news of the grace of Christ in the (New Testament) gospel. For Calvin, Christ is revealed in both the law and the gospel. Hence the title of Book II:

The Knowledge of God the Redeemer in Christ, First Disclosed to the Fathers Under the Law, and Then to Us in the Gospel

Accordingly, having established in chapters 1-5 that ‘The whole human race perished in the person of Adam’ (II.vi.1), Calvin delays his exposition of the Ten Commandments until he has introduced the good news of salvation in Christ in chapters 6 and 7. This is because the law of Moses is given in the context of the promises of blessing already given through Abraham:

Moses was not made a lawgiver to wipe out the blessing promised to the race of Abraham. Rather, we see him repeatedly reminding the Jews of that freely given covenant made with their fathers of which they were the heirs. It was as if he were sent to renew it (II.vii.1).

It is fitting, then, that of the three ‘uses’ or ‘functions’ of the law identified by Calvin, it is the third that is described as the ‘principal use’ (II.vii.12):

  1. ‘The law shows the righteousness of God, and as a mirror discloses our sinfulness, leading us to implore divine help’ (II.vii.6-9). The law, by calling us to love God wholeheartedly, makes us aware of our infirmity, so that we flee to God for his mercy.
  2. ‘The law restrains malefactors and those who are not yet believers’ (II.vii.10-11). There are some for whom the dread of divine punishment will act as a deterrent. ‘[T]his constrained and forced righteousness is necessary for the public community of men’ (II.vii.10).
  3. ‘Principally it admonishes believers and urges them on in well-doing’ (II.vii.12-13). This ‘proper purpose of the law’ is (1) to teach us ‘the nature of the Lord’s will’, and (2) to exhort and strengthen us in our obedience (II.vii.12).

When considering individual commandments from the Old Testament law, Calvin first looks for the deeper principles underlying the commandment, giving attention to ‘the reason of the commandment; that is, in each commandment to ponder why it was given to us’ (II.viii.8).

The second aspect of Calvin’s approach is to look beyond the prohibition to the opposite duty. I.e., when God commands us not to do something, we can infer that there are certain things that God does want us to do. For example,

in this commandment, ‘You shall not kill,’ men’s common sense will see only that we must abstain from wronging anyone or desiring to do so. Besides this, it contains, I say, the requirement that we give our neighbor’s life all the help we can (II.viii.9).

The resulting exposition of the Ten Commandments is really very helpful.