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.

In volume2 , the second of his three-volume reinterpretation of Christian theology, Paul Tillich comes to grips with the central idea of his system—the doctrine of the Christ. Man's predicament is described as the state of "estrangement" from himself, from his world, and from the divine ground of his self and his world. This situation drives man to the quest for a new state of things, in which reconciliation and reunion conquer estrangement. This is the quest for the Christ.

In volume 3, the third and last of his Systematic Theology, Paul Tillich sets forth his ideas of the meaning of human life, the doctrine of the Spirit and the church, the trinitarian symbols, the relation of history to the Kingdom of God, and the eschatological symbols. He handles this subject matter with powerful conceptual ability and intellectual grace.

The problem of life is ambiguity. Every process of life has its contrast within itself, thus driving man to the quest for unambiguous life or life under the impact of the Spritual Presence. The Spritual Presence conquers the negativities of religion, culture, and morality, and the symbols anticipating Eternal Life present the answer to the problem of life.