If all Scripture testifies of Christ, the law of God surely cannot be an exception. As we study the law in a seminary context, then, nothing can be more important than to study its witness to Christ. Ministers of the gospel need to learn how to preach Christ from the law.
In fact, the law bears witness to Christ in a number of ways, some of which I shall discuss in the following points.
1. The Decalogue presents the righteousness of Christ. When we say that Christ was the perfect lamb of God and the perfect example for the Christian life, we are saying that he perfectly obeyed God’s law. He never put any god before his Father. He never worshipped idols or took God’s name in vain. The Pharisees arguments to the contrary notwithstanding, he never violated the Sabbath command. So, the Decalogue tells us what Jesus was like. It shows us his perfect character.
2. The Decalogue shows our need of Christ. God’s law convicts us of sin and drives us to Jesus. It shows us who we are apart from Christ. We are idolaters, blasphemers, Sabbath-breakers, and so on.
3. The Decalogue shows the righteousness of Christ imputed to us. In him we are holy. God sees us, in Christ, as law-keepers.
4. The Decalogue shows us how God wants us to give thanks for Christ. In the Decalogue, obedience follows redemption. God tells his people that he has brought them out of Egypt. The law is not something they must keep to merit redemption. God has> redeemed them. Keeping the law is the way they thank God for salvation freely given. So the Heidelberg Confession expounds the law under the category of gratefulness.
5. Christ is the substance of the law. This point is related to the first, but it is not quite the same. Here I wish to say that Jesus is not only a perfect law-keeper (according to his humanity), but that according to his deity he is the one we honor and worship when we keep the law:
(a) The first commandment teaches us to worship Jesus as the one and only Lord, Savior, and mediator (Acts 4:12; 1 Tim. 2:5).
(b) In the second commandment, Jesus is the one perfect image of God (Col. 1:15; Heb. 1:3). Our devotion to him precludes worship of any other image.
(c) In the third commandment, Jesus is the name of God, that name to which every knee shall bow (Phil. 2:10-11; cf. Is. 45:23).
(d) In the fourth commandment, Jesus is our Sabbath rest. In his presence, we cease our daily duties and hear his voice (Luke 10:38-42).
(e) In the fifth commandment, we honor Jesus who has brought us as his “sons” (Heb. 2:10) to glory.
(f) In the sixth commandment, we honor him as the life (John 10:10; 14:6; Gal. 2:20; Col. 3:4), Lord of life (Acts 3:15), the one who gave his life that we might live (Mk. 10:45).
(g) In the seventh commandment, we honor him as our bridegroom who gave himself to cleanse us, to make us his pure, spotless bride (Eph. 5:22-33). We love him as no other.
(h) In the eighth commandment, we honor Jesus as our inheritance (Eph. 1:11) and as the one who provides all the needs for his people in this world and beyond.
(i) In the ninth commandment, we honor him as God’s truth (John 1:17; 14:6), in whom all the promises of God are Yea and Amen (2 Cor. 1:20).
(j) In the tenth commandment, we honor him as our complete sufficiency (2 Cor. 3:5; 12:9) to meet both our external needs and the renewed desires of our hearts.