Having summarized the course of Western history to show that it has culminated in despair over the meaninglessness of existence, Tillich proceeds to show how religious faith can provide the courage to cope with this despair and meaninglessness.
In doing so, Tillich adopts an idiosyncratic terminology that led some orthodox Christian commentators to criticize him and even to accuse him of not being a Christian. For one thing, he speaks of the “power of being,” the “ground of being,” and “being-itself” as apparent synonyms for God, making God less a being than a condition. In fact, Tillich specifically opposes any approach, such as the arguments for the existence of God, that would make of God a mere being among other beings rather than being-itself.
For Tillich there is a religious root to the courage to be, based on the relationship to being-itself. This relationship can be mystical if the emphasis is on uniting with ultimate reality, or it can be personal if the emphasis is on the individual encounter with God. He sees Martin Luther as an example of the personal approach, not dependent on institutions or collectives.
In Luther and the Protestant Reformers, Tillich sees the means to conquer the anxiety associated with guilt by accepting God’s acceptance, allowing oneself to have one’s sins forgiven by God. This requires courage because it means confessing one’s sins and accepting one’s guilt.
Similarly, Tillich sees a need to accept one’s death to deal with the anxiety associated with death. He does not support the popular belief in immortality of the soul, which he says is not truly Christian and which he says seeks to evade the fact of death. Instead, he emphasizes communion with God.
Tillich also argues against the popular notion that faith means believing unbelievable things. He sees faith as a state of being in which one is grasped by the power of being-itself and through which one can deal with the anxiety of meaninglessness by accepting it.
Tillich ends his book with a controversial discussion of the “God above God.” This is the God above the all-powerful tyrant that Tillich sees as the conventional God. He says it is necessary to go beyond this conventional God to be grasped by the God above God, faith in whom provides the courage to be.