Paul Tillich, a highly regarded thinker from Germany, who developped and completed his work in the US, was not only a theologian but also a philosopher. He used the philosophical method in order to articulate and justify theological theorems contained in Christian Revelation. According to Tillich, the essence and the existence are means of human being. The differentiation between these two, conducted from the religious point of view, is one of the basic issues for the German philosopher. The article makes an attempt to grasp this subject in accordance with Christian philosophy and to place it within the tradition of Platonic philosophy.