The author takes up Niebuhr's theology and presents it to be, at its heart, an attempt to grapple with the most powerful and most dangerous aspect of human nature: a quality Niebuhr describes as 'the will-to-power'. Lovatt argues forcibly that Niebuhr identifies the fundamental nature of human sin as having very specific qualities; and that Niebuhr, over his various works, develops a theology which seeks to deal effectively with this quality, both theologically and practically. Lovatt discusses the main areas of doctrine covered by Niebuhr, and considers how his position reflects his underlying agenda to grapple with the reality of the will-to-power. This leads to some important conclusions about Niebuhr, modern theology, and the present-day problem of evil.