This is, admittedly, a summary of a summary of Luther's thought on law and faith and good works. But it is a good one, penned by Peter Leithart as an introduction of a chapter on 2 Kings 17. (From his commentary published by Brazos Press). 2 Kings 17 chronicles the reasons why the Lord drove Israel, the Northern Kingdom, into exile.
Leithart summarizes Yeago's take on Luther's take on faith, the first commandment and good works. I like the thought that the Law does not demand a set of actions but rather a new heart of faith (1st commandment). It is form this new heart of faith, exclusive clinging to God, that a set of actions springs forth. The law then show that new heart the new way of life in which it naturally walks. I also like the insistence that before and after the Fall the law does not change but the object of that law, Adam, has changed.
Nothing in Christian theology is more important, Protestants often declare, than to distinguish rightly between law and gospel. Though this distinction has often been deployed in antinomian fashion that separates grace from any concern for moral order, this is, with regard to Luther as much as the Swiss Reformers, a deep misreading.
Far from renouncing moral order and the law's work in shaping of human action, Luther, Yeago argues, insists that "the bestowal of God's grace through the gospel is. ..the only true formation of the human heart, that which alone sets the heart truly in order" (1998, 164).
For Luther, distinguishing between the prelapsarian and the postlapsarian functions of the law is crucial. In Luther's own words, "when Adam had been created in such a way that he was, so to speak, drunk with joy towards God, and rejoiced also in all other creatures, then there was created a new tree for the distinction of good and evil, so that Adam might have a definite sign of worship and reverence toward God" (quoted in Yeago, 1998, 176).
Thus, for Luther the commandment is given to Adam so that 'Adam's love for God" could "take form in an historically concrete way of life," as the "concrete social practice of worship." After Adam's fall, the function and meaning of the law changes because Adam changes. The subject presupposed by the original commandment in the garden, "the subject that is drunk with joy towards God," is no longer there, and in his place is a person "who has withdrawn from God, who believes the devil's lies about God and therefore flees and avoids God" ( 1998, 177). Yet, when God renews a sinner by the Spirit, he restores him or her to something like Adam's relation to law. Understood spiritually, all commandments must be referred to the first, the demand to have no gods before God (1998, 176-77).
For graced human beings, the law comes as a call to faith. For Luther, "it is in a certain sense a misunderstanding of the divine commands to say that they demand particular behaviors; it is more accurate to say that they demand a heart that fears, loves, and trusts God, and that they offer such a heart the concrete form of life appropriate to it" (Yeago 1998, 181).
This does not make the concrete commandments optional, for one cannot truly love and fear God and ignore his word. Rather, "every commandment implicitly but also intrinsically calls for a particular sort of person, a particular mode of human existence within which the specific behaviors also called for can play their proper role" (1998, 181). The law is not fulfilled apart from the commitment of the heart: Luther says, "His law also calls for the ground of the heart and cannot be satisfied with works," and this is a demand that we cannot fulfill (1998, 181-82 [emphasis original]).
This means, Luther says, that "it calls for Christ, and presses us towards him, so that we first become different people through his grace in faith, and become like him, and then do genuine good works" (1998, 183). The law announces, "You must have Christ and the Spirit," which means, Yeago argues, that "the law calls for faith, since faith is precisely the New Testament name for the bonding of our lives with Christ and the Spirit" (1998, 184).
Peter, Leithart, 1 & 2 Kings (Brazos Theological Commentary on the Bible, 249-50.