Following the commandments of God is one mark of the true Christian. After all, Christ lives in His people (Gal. 2:20), and since Jesus’ food is to do the will of His Father (John 4:34), He certainly works in us so that we see following God as essential to our sustenance. Yet may we never forget that our obedience is always grounded in grace, for apart from the Lord changing our hearts, we have no desire to please Him (Rom. 8:7–8). Following God’s law, therefore, does not mean obeying it to secure our right standing in His heavenly court, for we can stand before Him by His grace alone (Eph. 2:8–9). Also, following God’s law does not mean obeying it in order to boast of how we are more godly than others. We are always to confess our failures and remember that “there but for the grace of God go I” (Luke 18:9–14).
Until we trust Christ, God’s law can merely restrain the extent of our sinning, encourage us to love sin, and condemn us as sinners who need the Savior (Rom. 7:8; Gal. 3:23–25; 1 Tim. 1:8–11). But once we are converted, God’s law becomes something in which we rejoice. Redeemed hearts no longer experience the Lord’s regulations as burdensome (1 John 5:3), and they see the importance of keeping “the commandments of God” (1 Cor. 7:19). Through obedience, we thank Him for the right standing granted to us by grace alone through faith alone in Christ alone (Rom. 5:12–6:14).
What, then, are the commandments of God that we must keep? This question is not a simple one, especially since Paul and the other New Testament writers use the word law in a number of different ways. Clearly, however, God’s eternal law is not coterminous with the Mosaic law, at least for the new covenant believer. After all, Paul draws a distinction between circumcision, which was an old covenant commandment, and the commandments of God (1 Cor. 7:19). Still, God’s eternal moral law is found within the Mosaic law, which also includes many regulations (for example, the sacrifices) that were in force only for a time in order to point Israel to Christ.
Historically, as exemplified in question and answer 92 of the Heidelberg Catechism, Reformed theology has viewed the Ten Commandments as the heart of God’s law. These ten elaborations of the fundamental principles of love of God and neighbor (Matt. 22:34–40) form the basic outline of what it means to please our Creator.