This is the first part of Paul Tillich's three-volume Systematic Theology, one of the most profound statements of the Christian message ever composed and the summation and definitive presentation of the theology of the most influential and creative American theologian of the twentieth century.

In this path-breaking volume Tillich presents the basic method and statement of his system—his famous "correlation" of man's deepest questions with theological answers. Here the focus is on the concepts of being and reason. Tillich shows how the quest for revelation is integral to reason itself. In the same way a description of the inner tensions of being leads to the recognition that the quest for God is implied in finite being.

Here also Tillich defines his thought in relation to philosophy and the Bible and sets forth his famous doctrine of God as the "Ground of Being." Thus God is understood not as a being existing beside other beings, but as being-itself or the power of being in everything. God cannot be made into an object; religious knowledge is, therefore, necessarily symbolic.