We are told [in Article Six of the Formula of Concord] that Christians still stand in need of the punishments of the Law as well as of other punishments and plagues for this reason, “that they be aroused and follow the Spirit of God.” This is not to be understood as though the threatening and punishment of the Law were in itself an encouragement and, therefore, an inducement to obedience. No, a regenerate person nevermore does anything good by constraint of the Law. However, the Law with its teaching, warning, threatening, does indeed make room for the Gospel and prepares the way for it also where the conduct of the Christians is concerned. The Law reminds the Christian of his continual, daily sinning, disquiets him and becomes an occasion for him to seek with new zeal after righteousness and holiness. That willingness and that joyousness to obedience, which, of course, proceed alone from the Gospel, begin in the heart filled with anxiety because of inherent weakness.
But now we are chiefly interested in that part of the quotation from our Confession when it speaks of “the teaching of the Law.” Is it really so that believers need the doctrine of the Law for their good works, being unable to find the right way and erring in darkness without such doctrine? True, the Law is “a rule and standard of a godly life.” However, our Confession clearly teaches that believers “because of the Old Adam, which still clings to them,” and “because they are not renewed in this life perfectly or completely,” still need “the doctrine of the Law.” It teaches that if in their nature they were entirely free from sin, they would need absolutely no Law, that they would without any instruction of the Law do what they are in duty bound to do according to God’s will. Hence the Law is rule and standard for the walk of the regenerate in so far as they have not been born again, in so far as they still have flesh and are flesh. A Christian, in so far as he is born again, is driven by the Holy Ghost, whom be has received in the Gospel. Therefore he does willingly without coercion, of his free will, what is pleasing to God just as the sun, moon, and all the constellations of heaven of themselves gleam and, unobstructed, complete their regular course. Thus the good works of the Christians are fruits of the Spirit, fruits which grow of themselves. But the Spirit of God, who governs the children of God in what they do or do not do, certainly knows of Himself the good and gracious will of God and needs no teaching, no instruction. He guides and directs and drives according to His mind and will, and that is God’s mind and will, and thus leads us into the land of uprightness and teaches us to do according to God’s good pleasure. He is the Spirit of prayer, a Spirit of joy and gentleness, a Spirit of correction and fear of the Lord. A Christian therefore, in so far as he is a temple of the Holy Ghost, in so far as the Spirit of God has gained room within him, walks in paths of uprightness, lives in the Law, the will of God, knows, desires, and does what God wants “without any teaching of the Law.” But in so far as he still has the Old Adam, he is still subject to the error of sin and therefore often has the wrong conception of what he owes God and man, and loves to choose his own ways and works, his own manner of serving God. For this reason he still needs “the written Law,” the teaching of the Law, in order that he does not serve God according to his “own thoughts,” as our Confession notes. The Law exposes and condemns all self-chosen and self-devised holiness and piety. So the Law ever observes its prescribed course, even when it serves the Christians as rule and standard of their walk and life. Here too that expression of Scripture, the Law was given because of sin, remains perfectly lawful.
“Law and Gospel According to Their Several Effects”, trans. Rev. W.H. Bouman