To his own age, Ludwig Feuerbach seemed a Prometheus, a revolutionary who robbed Christianity of its superhuman aura and pointed to the anthropological origin of all religions. In the eyes of the Young Hegelians, among them Karl Marx, he appeared to have prepared the way for humanity's recovery of its rightful heritage and "alienated essence." Feuerbach seemed to show the way to many liberals in the struggle for human self-understanding, authentic existence, and social freedom. The book that contributed most to this reputation and that is still generally considered his most important work is Das Wesen des Christenthums (1841; translated as The Essence of Christianity, 1854). Less than a decade after its publication, however, Feuerbach's fame had ebbed. Decried by theologians and conservative Idealist philosophers, Feuerbach refused to participate in the Revolution of 1848 and thereby alienated himself from Marx, Friedrich Engels, and the "scientific socialists." Skeptical of the political capacities...