The three purposes and functions of God’s Law are:
- The threat and punishments of God’s Law, in a measure, check the coarse outbursts of sin. In this way the Law maintains outward discipline, order and morality in the world, and curbs outward evil. The Law is a curb. This is called the first use of the Law.
1 Tim. 1:9: The law is not made for a righteous man, but for the lawless and disobedient, for the ungodly and for sinners, for unholy and profane, for murderers of fathers and murderers of mothers, for manslayers.
- The Law teaches us rightly to know our sin before God. The Law is a mirror. This is the chief purpose of the Law. It is called the second use of the Law.
Rom. 3:20: By the Law is the knowledge of sin.
Rom.7:7: I had not known sin but by the Law, for I had not known lust, except the Law had said: Thous shalt not covet.
Gal. 3:17: The Law was our schoolmaster to bring us unto Christ, that we might be justified by faith. - The Law shows believers in Christ what their God-ordained responsibilities are in this life. The Law is a rule. This is called the third use of the Law.
Ps. 119:105: Thy Word is a lamp unto my feet, and a light unto my path.
Rom. 3:31: Do we then make void the law through faith? God forbid; yea, we establish the Law.
Luther teaches the third use of the Law already in his explanations of the Small Catechism, for he has written them so that we, as the children of God, would “also lead a holy life according to” the Word of God. (See the explanation of the First Petition.)
