The question of boundaries is fundamental to the philosophy of religion. This article analyzes and compares two influential philosophers in the field, Kierkegaard and Tillich. Though usually they are represented as exponents of the same (existentialist-protestant) tradition, a different perception of the main questions and possibilities for philosophical theology to answer them guides them to radically different conclusions in topics of the philosophy of religion. On the other hand, a closer look at how they understand faith (pistis) gives new possibilities to interpret the ideas of Kierkegaard and Tillich rather than to accept "chrestomatic" analyzes. Tillich's implicit loyalty to platonic and hegelian ideas subordinates the existential aspects of his system to answers which can be described as a "gnostic" understanding of faith and knowledge. This violates the limits for theoretical knowledge which were set by Kierkegaard. Such a tillichian ontological loyalty explains that an ontological search is implicated in every religious experience. This basic presupposition of interaction with the sacred for Tillich lets us view Kierkegaard's famous interpretation of biblical myths critically, and to argue that these stories do not mean that the only possible faith is "blind" faith. This opens a path for Tillich to rationalize every aspect of Christianity, and to talk about "true God", God beyond the gods of actual religions.