Hauerwas uses his Gifford Lectures to explore the possibility of natural theology and the connection between doctrine and ethics. His basic thesis is that the truth of Christianity cannot be demonstrated, only believed and witnessed. The most convincing witness is that of a life lived in conformity with the gospel, which suggests the possibility that these teachings might be liveable, and thus true.

The argument is carried forward by sustained interaction with three previous Gifford lecturers: William James, Reinhold Niebuhr and Karl Barth. James’ Varieties of Religious Experience demonstrates the attempt to understand the persistence of religion in terms of human psychology; Niebuhr’s Nature and Destiny of Man appears to be a contrasting work of orthodox Christian doctrine, but Hauerwas attempts to show that Niebuhr’s methodology is in fact little different from James’. In both cases, religious ideas are held to be true insofar as they are useful; Niebuhr regards more of Christian doctrine as retrievable on such a basis, but that is not saying very much.

Karl Barth stands in radical contrast. He refuses, on good intellectual grounds, to accept that there is any possibility, or any need, to demonstrate the truth of the Christian gospel beginning from more basic premises. Truth comes from without, as revelation; as such, it can never be demonstrated, but must be received, and it can never be proved, but must be witnessed. The lectures end with a consideration of the category of witness, with Barth himself, John Howard Yoder and Pope John Paul II being held up as examples of lives that would be inconceivable if the gospel were not true.