We desperately want to believe the best about ourselves. And with effort we can shrug off inner conviction. But it is harder to ignore God’s written word. Young King Josiah is an example for us. When he heard the words of the law “he tore his clothes” in humility; his “heart was penitent” (2 Kings 22:11, 19). Josiah knew that Judah was offending a holy God: “For great is the wrath of the Lord that is kindled against us” (2 Kings 22:13). Duly convicted he fought against idolatry with a holy hatred. And he believed God’s promise to pass-over the sin of the penitent. Josiah reinstituted the Passover which pointed to Christ and his perfect righteousness as the only protection against the angel of death. Use God’s law to come, as a needy sinner, to a perfect Savior.

Unlike every other religion Christianity is fundamentally a message of grace. True believers are “not under the law, as a covenant of works, to be thereby justified or condemned” (cf. Rom. 6:14) Believers are saved by grace alone through faith alone in Christ alone.

But a misunderstanding of grace leads to a confused relationship with the law. Some think that any loyalty to law indicates legalism. Others ridicule God’s law, calling it inconsistent. After all, they reason, Old Testament prohibitions against homosexuality run alongside rules against mixing seeds in a field and materials in a garment (Lev. 18:22; 19:19; 20:13). Even Christians who are conscientious about God’s law can be unclear about which obligations are enduring and which have been fulfilled. We need a better understanding of God’s law so that we can use it in a way that honors him.

How Should I Understand God’s Law?

The principle of God’s law is very simple. The Creator imposes his values on his creatures. That truth never changes. In fact, in the New Testament Christ doubles-down on the necessity of rigorous obedience. In the Sermon on the Mount sincere submission to God’s law distinguishes citizens of God’s kingdom from citizens of the world. The law contrasts for us good works and works of the flesh. And we need that distinction. We must do good works which are only those “God hath commanded in his holy word” (16.1).

A right attitude toward God’s law requires understanding its history. The creation account reveals God’s right to order his creature’s activities. In the beginning God established boundaries for all of creation (Job 38:8–11). To his people he outlined definite expectations. You shall “fill the earth and subdue it” (Gen. 1:28). “You shall not eat” of the tree of the knowledge of good and evil (Gen. 2:17). He didn’t simply tell people to “be good,” whatever that means; he told us how to live.

Even after Adam and Eve violated the covenant of works God continued to require “personal, entire, exact, and perpetual obedience.”. In time God revealed himself more personally to a single tribe of people. When he rescued Israel from slavery in Egypt he made them into a holy nation by way of covenant, a binding agreement, summarized by the Ten Commandments (Ex. 19:6). And these laws are still “a perfect rule of righteousness.” If the two great commandments are to love God and our neighbor, these ten laws define that love (Matt 22:37–40). We love God by putting him first, worshiping him properly, respecting his name, and honoring his schedule for work and rest. We love our neighbor by respecting human authority, promoting life, practicing sexual integrity, stewarding our resources, telling the truth, and being content. 

So far so good. All serious Christians recognize ten commandments as a summary of God’s will. But what about the hundreds of other Old Testament laws? In addition to the abiding moral law God also gave Israel two categories of laws which do not apply to us today in the same way.

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