One looks almost in vain for a major discussion of sin during the twentieth century. Does guilt before God still have meaning in the context of modern developments such as Marxism and psycho-analitical approaches to who man is? This essay attempts to examine the way that theology has sought to come to terms with the idea of sin during the twentieth century. It limits itself to a study of three representative theologians (Karl Barth, Reinhold Niebuhr, and Norman Pittenger), expounding and assessing their constructions, noting how they have responded to recent challenges, and seeking to learn from their strengths and weaknesses.