Reinhold Niebuhr continues to be appreciated by political thinkers for his independent, contrarian judgements as regularly as he is criticised by theologians for abandoning core elements of the Christian faith in an effort to accommodate the cultural expectations of modernity. The two assessments are hard to reconcile, but Niebuhr himself thought that his political insights were grounded in theology, and he insisted that responsible faith enables discriminating judgements between practical political alternatives. Scott Erwin provides a measured defence of Niebuhr's position by tracing the development of his theology from the beginning of World War II through to The irony of American history, published in 1952, in the middle of the Cold War. Erwin argues for the continuity of Niebuhr's work through these most productive and influential years of his career, showing that the theology of history set out in the Gifford Lectures of 1939–40 shapes the account of American history and the cautious affirmation of American democracy in Irony. Irony is not an alternative to divine judgement, but a subtle anticipation of it, and a gentle nudge in the direction of faith for those who might otherwise be content to trust in their own righteousness. Erwin makes this case conceptually, analysing key themes in Niebuhr's most important writings to show connections between ideas that Niebuhr himself rarely sets out systematically in one place. The work is also a splendid historical study. Erwin works through Niebuhr's numerous occasional writings, unpublished papers and correspondence, enabling readers to follow the stream of ideas in relation to events. We arrive at Irony with an appreciation for Niebuhr's experience, as well as his ideas, and we begin to see why it seemed theologically important to him to present his interpretation of American history without explicit theological foundations – why he saw this, indeed, as a kind of Christian witness. Erwin's own judgement on Niebuhr's project is one of qualified affirmation. Understanding Niebuhr's thought as a whole and the particular challenges of his time, he cannot agree with recent critics who think that Niebuhr simply recasts Christianity in the mould of modern thought. But he is not sure that irony can avoid a descent into cynicism without a more explicit affirmation of Christian hope.