I suggest that we call the dimension of depth the religious dimension in man’s nature. Being religious means asking passionately the question of the meaning of our existence and being willing to receive answers, even if the answers hurt. Such an idea of religion makes religion universally human, but it certainly differs from what is usually called religion. It does not describe religion as the belief in the existence of gods or one God, and as a set of activities and institutions for the sake of relating oneself to these beings in thought, devotion and obedience. No one can deny that the religions which have appeared in history are religious in this sense. Nevertheless, religion in its innermost nature is more concerned about one’s own being and being universally.
~ Paul Tillich, The Lost Dimension in Religion (1960)