Faith as ultimate concern is an act of the total personality. It happens in the center of the personal life and includes all its elements. Faith is the most centered act of the human mind. It is not a movement of a special section or a special function of man's total being. They all are united in the act of faith.
Paul TillichGod does not exist. He is being-itself beyond essence and existence. Therefore to argue that God exists is to deny him.
Paul TillichSpirit is the presence of what concerns us ultimately, the ground of our being and meaning.
Paul Tillich