Of what use is the moral law to all men?

The moral law is of use to all men, to inform them of the holy nature and will of God,[1] and of their duty, binding them to walk accordingly;[2] to convince them of their disability to keep it, and of the sinful pollution of their nature, hearts, and lives;[3] to humble them in the sense of their sin and misery,[4] and thereby help them to a clearer sight of the need they have of Christ,[5] and of the perfection of his obedience.[6]

1. Lev. 11:44-45

   For I am the Lord your God. Consecrate yourselves therefore, and be holy, for I am holy. You shall not defile yourselves with any swarming thing that crawls on the ground. For I am the Lord who brought you up out of the land of Egypt to be your God. You shall therefore be holy, for I am holy.

   Lev. 20:7-8

   Consecrate yourselves, therefore, and be holy, for I am the Lord your God. Keep my statutes and do them; I am the Lord who sanctifies you.

   Rom. 7:12

   So the law is holy, and the commandment is holy and righteous and good.

2. Micah 6:8

   He has told you, O man, what is good;
   and what does the Lord require of you
   but to do justice, and to love kindness,
   and to walk humbly with your God?

   James 2:10-11

   For whoever keeps the whole law but fails in one point has become accountable for all of it. For he who said, “Do not commit adultery,” also said, “Do not murder.” If you do not commit adultery but do murder, you have become a transgressor of the law.

3. Psa. 19:11-12

   Moreover, by them is your servant warned;
   in keeping them there is great reward.

   Who can discern his errors?
   Declare me innocent from hidden faults.

   Rom. 3:20

   For by works of the law no human being will be justified in his sight, since through the law comes knowledge of sin.

   Rom. 7:7

   What then shall we say? That the law is sin? By no means! Yet if it had not been for the law, I would not have known sin. For I would not have known what it is to covet if the law had not said, “You shall not covet.”

4. Rom. 3:9, 23

   What then? Are we Jews  any better off? No, not at all. For we have already charged that all, both Jews and Greeks, are under sin….

   …for all have sinned and fall short of the glory of God…

5. Gal. 3:21-22

   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. But the Scripture imprisoned everything under sin, so that the promise by faith in Jesus Christ might be given to those who believe.

6. Rom. 10:4

   For Christ is the end of the law for righteousness to everyone who believes.

Question 95, Westminster Larger Catechism