This paper deals with the problem of a Christian foundation of Western philosophy the existential philosophy of Jean-Paul Sartre, in this case. The author tries to show that in spite of his declared atheism Sartre's metaphysics latently comprises the ontological "melancholy for God" and that the "absence of God" is the primary principle for "building" of the whole metaphysical system of Sartre and of his concept of human consciousness and subjectivity. As the "core" of the existential philosophy in general (be it religious or "atheistic") is the problems of personality ("being-to-death", "the border situation", freedom, guilt and responsibility) - so, its problematic is close to traditional Christian anthropology.