Question 15: Since no one can keep the law, what is its purpose?

Answer 15: That we may know the holy nature and will of God, and the sinful nature and disobedience of our hearts; and thus our need of a Savior. The law also teaches and exhorts us to live a life worthy of our Savior.

Even though no one can keep the law perfectly it is still important. More than that, Paul calls it holy, and righteous, and good (Romans 7). Psalm 119 over and over again praises and rejoices in the law. Psalm 119:92 says, “If your law had not been my delight, I would have perished in my affliction.” And our answer gives us three good uses of the law. First, that we may know the holy nature, character, and will of God. Our greatest need is to know God. AW Tozer. Without the law, we have a truncated view of God. The law shows us what God is like. The first table of the law - commands one through four - shows us the nature of God by revealing what he requires of us in relation to him. The second table of the law - commands five through ten - shows us the nature of God by revealing what he requires of us in relation to other image bearers of God. God is holy and righteous and good and thus his law is. 

The second use of the law is to show us the sinful nature and disobedience of our hearts and thus our need for a Savior. When we honestly assess how we measure up to God’s law - even on our best days - we realize how woefully we fall short. Paul said that nobody can be accepted to God through law keeping because the law is meant to show us our sinfulness. This is God’s intention of the law. In Galatians, Paul likens the law to a schoolmaster or a tutor to lead us to Christ. The law teaches us that we are sinners and rebellious and in need of a Savior. The law drives us to believe in, cherish, and cling to Christ.

And the third reason for the law is to teach and exhort us to live worthy of our Savior. The law is good to show us God’s standards for holy living. Not as a means to earn salvation, but as saved people with new hearts and the law of God written on our hearts, longing to please the Lord. This is often a forgotten element of the continuing importance of the law for believers. We take the words of Paul in Galatians where he says we are no longer “under the law” and assume that means obedience to the command, “You shall not covet” is optional. We are not under it in the sense that our obedience merits anything from God. We are not under the law when it comes to our justification. But we are most certainly obligated to obey our Lord out of love for him and submission to his lordship, which is why James says it is the one who is an effectual doer of the law that is blessed.

Romans 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