The act in which a man actualizes his essential centeredness is the moral act. Morality is the function of life by which the realm of the spirit comes into being. Morality is the constitutive function of spirit. A moral act, therefore, is not an act in which some divine or human law is obeyed but an act in which life integrates itself in the dimension of spirit, and this means as personality within community. Morality is the function of life in which the centered self constitutes itself as a person; it is the totality of those acts in which a potentially personal life process becomes and actual person.This is a definition of morality I can live with. Moral acts are all those things I do that make me into who I am. I act immorally when I do things that goes against who I really am.
Systematic Theology III, 38.
Some would say that this is an awfully self-centered view of morals. Isn't morals about who we relate to each other? It is, but that is not what morals is, but what good morals is. As Tillich write, when life integrates itself in the dimension of the spirit, this means that it becomes a personality within community. A person cannot be except in connection with others, it is the effect our acts have on our relationships that determine who we are.
This is why ethical discussion on an abstract level so often is pointless, if not evil. Morals is a concept relevant only in that web of relationships, one cannot separate oneself from it and discuss morals objectively. Such discussion - though I realize a community need norms for acceptable behaviour - so easily turns into a kind of manipulation of these relationships in order to override our essential morality. If our "rules of ethics" say something is ok, we do it event if we know it will hurt people.