This view of believers as saints and sinners at the same time, and as perfectly justified and imperfectly sanctified, with a fierce civil war raging within them between their old and new natures (see Romans 7), requires great care in the proper application of Law and Gospel. A number of things must be and remain quite clear: the Law is the standard and measure of good works, but it lacks the power to produce or motivate them. Only the Gospel does that. yet the Gospel does not simply liberate us from the law, as antinomianism imagines; rather, it liberates us from the condemnation and the coercion of the Law, so that according to our new nature we are now free to love and obey it. The worst feature of antinomianism is that in refusing to see the Law as applicable to Christians, it inadvertently turns the Gospel into Law, that is, into a rule and demand for good works! Such radical confusion of Law and Gospel in principle destroys both of them. It is true that the Law “always accuses”. But this refers to the chief, or second, use of the Law, which cannot be separated but must be distinguished from the third use. For the new creation within us loves and treasures God’s will as expressed in His Law, even while the old, rebellious flesh within us needs to be on the receiving end of the full force of the Law’s condemnation. Having been saved by grace and through faith alone, we are “God’s workmanship, created in Christ Jesus to do good works, which God prepared in advance for us to do” (Eph. 2:10 NIV).
+Kurt E. Marquart+, “The Third Use of the Law in the Formula of Concord”, from “You, My People, Shall Be Holy“