Here's part of the reason I find Hauerwas so congenial to reformed (in this case, vantillian) ways of thinking:

Michael J. Quirk: Your Gifford lectures contain critical appraisals of both William James and Reinhold Niebuhr, as well as the astonishing claim that Karl Barth is the most successful natural theologian of the twentieth century. One usually finds Barth depicted as the resolute enemy of all natural theology. Could you explain how you came to this understanding of Barth?

Stanley Hauerwas: It fits as part of my larger argument that a natural theology is unintelligible separated from a full doctrine of God. And of course what a full doctrine of God entails is an understanding, first of all, that God is not part of the metaphysical furniture of the universe. What many of the Gifford lecturers have assumed is what Nicholas Wolterstorff has called an "evidentialist apologetic" that tried to show that God, as an empty signifier, must exist. And I'm trying to show that if you could successfully show that that God must exist then you would have evidence that the Christian God does not exist. Because the Christian God is the God who created gratuitously. So there can be no necessary relationship between creation and God from the Christian point of view. Accordingly, the whole modernist enterprise that the Gifford lectures named was based upon a decisive metaphysical mistake vis-а-vis the Christian doctrine of God.