Seeing that the Ten Commandments were addressed to the Jewish nation to govern their life according to the stipulations of the Mosaic covenant, one might ask the question “How do the Ten Commandments apply to Christians?” That’s a fair question! There are some who would argue that the Law doesn’t apply to us because “we’re not under law, but under grace” (Romans 6:14). Jesus said that he came to “fulfill the law” (Matthew 5:17). However, if the Ten Commandments represent the moral character of God, and since we’re called to be imitators of God (Ephesians 5:1), then the law (namely, the Ten Commandments) must have some use to us on this side of the cross.
The Protestant Reformers developed the idea of the Three Uses of the Law. The first use of the law was the pedagogic use of the law. This use of the law shows us our sin in relation to God’s holy standards. The law condemns and convicts and drives us to Christ. The second use of the law is the civil use of the law. In this capacity, the law restrains evil in society by ascribing punishment to transgressions of the law. The third use of the law is the didactic use of the law. In this mode, the law serves as a guide for Christian behavior (very similar to the way it was supposed to for the Israelites). The didactic use of the law teaches us God’s character and provides instruction on how Christians ought to live; in particular how to love God and love their neighbor. Specific teaching on the Ten Commandments appears in both the Heidelberg Catechism and the Westminster Catechisms – classic documents on teaching Christian doctrine to children or new believers.
So while we are “not under law, but under grace,” we are not free to live any which way we choose. Christians have the law written on their hearts (Jeremiah 31:33), but we still need to obey what our Lord taught. That is why we have his written word. Our redeemed spirits reside in unredeemed flesh and we need a reminder of how we ought to live. The good news is that our position before God is not based on our observance to the law, but on the fact that Christ fulfilled the law on our behalf (Romans 8:4). Our obedience to the law serves as our ‘love offering’ to God (John 14:23).