In accordance with their essential nature, morality, culture and religion interpenetrate each other. They constitute the unity of the spirit, wherein the elements are distinguishable but not separable.I fell the connection between religion and culture that Tillich describes here is particularly interesting. It is a relation of interdependence. Culture needs religion to have "depth" or "substance". Religion needs Culture to create a universe of meaning in which it can exist. Culture provides religion with a form.
Morality, or the constitution of the person as person in the encounter with other persons, is essentially related to culture and religion. Culture provides the contents of morality - the concrete ideals of personality and community and the changing laws of ethical wisdom. Religion gives to morality the unconditional character of the moral imperative, the ultimate moral aim the reunion of the separated in agape, and the motivating power of grace.
Culture, or the creation of a universe of meaning in theoria and praxis, is essentially related to morality and religion. The validity of cultural creativity in all its functions is based on the person-to-person encounter in which the limits to arbitrariness are established. Without the force of
the moral imperative, no demand coming from the logical, aesthetic, personal and communal forms could be felt. The religious element in culture is the inexhaustible depth of a genuine creation. One may call it substance or the ground from which culture lives. ...
Religion, or the self-transcendence of life under the dimension of spirit is essentially related to morality and culture. There is no self-transcendence under the dimension of the spirit without the constitution of the moral self by the unconditional imperative, and this self-transcendence cannot take form except within the universe of meaning created in the cultural act.
Systematic Theology III, 95.
It should be noted that Tillich avoids to create a hierarchy of morals, religion and culture. Essentially they are one. Under the condition of existence they are separated, but they are still connected.