 Throughout the course of his work, Marcel arrived at an essentially theistic, specifically Christian, worldview, leading many to describe him as a Christian or theistic existentialist (especially in opposition to Sartre). Indeed, some thinkers regard Marcel’s philosophical writings on religious belief as his most profound contribution to philosophy: “From the beginning of his philosophical career, Marcel’s main interest has been the interpretation of religious experience, that is, of the relation between man and ultimate reality” (Cain, 1979, p. 87). Marcel’s early reflections, especially in Being and Having, laid the seeds for his conversion to Catholicism at the age of 40, though he believed that his philosophical ideas, and central Christian themes, though complementary, were in fact independent of each other: “It is quite possible that the existence of the fundamental Christian data may be necessary in fact to enable the mind to conceive some of the notions which I have attempted to analyze; but these notions cannot be said to depend on the data of Christianity, and they do not presuppose it . . . I have experienced [the development of these ideas] more than twenty years before I had the remotest thought of becoming a Catholic” (Marcel, 1995, pp. 44-45). Marcel became a Catholic when the French novelist, François Mauriac (1885--1979), recognized various themes in his writing concerning commitment, forgiveness, moral character and the religious justification of the moral order. Mauriac wrote to Marcel and explicitly asked him whether he ought not to join the Catholic Church, a call to which, after a period of reflection, Marcel assented. It is noteworthy that his conversion did not significantly change his philosophy, although it did lead to an increased focus on how various experiences, especially moral experiences, may point to the presence of the transcendent in human life.