Theological prolegomenon

This is all a bit niche interest, although it is pretty sweeping in its scope. It is a useful survey of two different responses to the Enlightenment critique of natural theology:

Prior to the Enlightenment, Lutheran scholastic orthodoxy used the concept of the natural knowledge of God to demonstrate God's existence. The Bible, by way of contrast, was regarded as a supernatural source of supernatural revelation. When this scheme was subjected to the critique of the Enlightenment, the consequence was that language about God became irrelevant to genuine knowledge, and the pathway was cleared for modern secularity. But Luther's theme of the law as the antithesis of the gospel had the potential of escaping the Kantian critique. Thus Lutheran theology would have in the category “law” a prolegomenon to the gospel which could make the transition from pre-modern to modern culture without giving up its essential proclamation. If "law" means whatever calls us into question before God, then we can see it functioning as prolegomenon in theologians as diverse as Theodosius Harnack (d. 1889), Werner Elert (d. 1954), and Paul Tillich (d. 1965), as well as in the work of contemporary Lutheran theologians Gerhard Forde and Robert Jenson.

Karl Barth's response to the critique of the Enlightenment and to the Liberal theology of the 19th Century was to reject the idea of prolegomenon altogether. If grace is revelation and revelation is grace, then the antithesis between law and gospel simply disappears. The revelation of God, whether law or gospel, is gracious.

(pp. 414-415, Walter R Bouman, "The Concept of the 'Law' in the Lutheran Tradition" Word & World 3/4 (1983))

The whole article is fairly good. I think the author is right that there are strengths and weaknesses in both responses.