This study analyzes the essential concepts of the existential personality psychology as indicated in overall literatures written by May and clarifies the reciprocal principles of those concepts, and identifies the integrated existential understanding of human personality in depth based on a lens of existence. For this purpose, this study first categorizes the structures of personality categorizes such as problems of existential personality, a recovery and maturity of existential personality. By clarifying the problems of existential personalty with the ontological anxiety, limits, and the fate of existence, this study pursues the appropriated solution about problems of personality by the deeper understanding about the predicament of human beings under the existential condition. In order to do some possible application for Christian counselling, this study tries to facilitate an interdisciplinary dialogue between May and Tillich by enhancing the theological perspectives on the existential personality in the literatures written by May.