According to the Puritans, the law of Moses has two basic functions: as a “covenant of works,” it condemns the sinner who disobeys it; as an expression of God's holy will, it directs the conduct of the people of God. For the Christians, the first of these functions is at an end, and this is what Paul means when he asserts that Christians are not “under the law” (Rom. 6:14-15). But the second of these functions remains fully in place, as Paul also suggests when he claims that the gospel “establishes the law” (3:31).
Douglas Moo