“The law is a divine doctrine which reveals the righteousness and immutable will of God, shows how man ought to be disposed in his nature, thoughts, words, and deeds in order to be pleasing and acceptable to God, and threatens the transgressors of the law with God's wrath and temporal and eternal punishment. For, as Luther says against the nomoclasts, ‘Everything that rebukes sin is and belongs to the law, the proper function of which is to condemn sin and to lead to a knowledge of sin’ (Rom. 3:20; 7:7). Since unbelief is a root and fountainhead of all culpable sin, the law reproves unbelief also.” (FC SD V 17)
“The Gospel, strictly speaking, is the kind of doctrine that teaches what a man who has not kept the law and is condemned by it should believe, namely, that Christ has satisfied and paid for all guilt and without man's merit has obtained and won for him forgiveness of sins, the ‘righteousness that avails before God’ [Ro 1:17; 2 Co 5:21], and eternal life.” (FC Ep V 4)
“The word ‘Gospel’ is not used in a single sense in Holy Scripture, and this was the original occasion of the controversy. Therefore we believe, teach, and confess that when the word ‘Gospel’ means the entire doctrine of Christ which he proclaimed personally in his teaching ministry and which his apostles also set forth (examples of this meaning occur in Mark 1:15 and Acts 20:24), then it is correct to say or write that the Gospel is a proclamation both of repentance and of forgiveness of sins.” (FC Ep V 6)
Law and Gospel do not differ if Law is taken in a broad sense, as in Is 2:3, or if Gospel is taken in a broad sense, as in Mk 1:1. They do not contradict each other. Both are God’s Word; both are in the OT and NT; both are to be applied to people everywhere, including Christians.
The fact that Law and Gospel differ in their narrow sense is suggested or indicated, e.g., Zech 11:7; Mt 13:52; Lk 12:42; Ro 10:4; Gal 3:24. The difference was used, e.g., 2 Sam 12:1–14: Lk 7:36–50; Acts 2:37–39; 16:27–31; 1 Co 5:1–5; 2 Co 2:6–8.
Differences: (a) The Law was written into man’s heart: the Gospel is not known by nature, but was revealed through Jesus and the Word of God. (b) The Law contains commandments of what we are to do and not to do and how we are to be; the Gospel reveals what God has done and still does for our salvation. (c) The Law promises eternal life conditionally; the Gospel promises it freely. (d) The Law demands perfect fulfillment and pronounces curses and threats if there is no perfect fulfillment; the Gospel has only promises and comforting assurrances. (e) The purpose of the Law is to serve as a curb, mirror, and rule (see also FC VI); the purpose of the Gospel is to forgive sins and give heaven and salvation as a free gift.
Law and Gospel are both operative in conversion. But the very nature of justification excludes the Law and leaves the Gospel as the only means whereby God justifies the sinner. The incentive power of the Gospel and the criterion of the Law are operative in sanctification. WFG
W. Geihsler, “The Law and the Gospel,” The Abiding Word, I, ed. T. Laetsch (St. Louis, 1946), 105–123; C. F. W. Walther, The Proper Distinction Between Law and Gospel, reproduced from the Ger. ed. of 1897 by W. H. T. Dau (St. Louis, 1929); W. Elert, “Gesetz und Zorn Gottes,” Morphologie des Luthertums, I (Munich, 1931; improved print., 1952), 31–39, tr. W. A. Hansen, “The Law and the Wrath of God,” The Structure of Lutheranism, I (St. Louis, 1962), 35–43; T. M. McDonough, The Law and the Gospel in Luther (London, 1963).