The purpose of this study is to develop the problem of the human estrangement and salvation by ontological theology of Paul Tillich. It would be reconsider the meaning of the New Being and the power of salvation by understanding on correlation of existence and Christ. Existentialism is an analysis of the human predicament. And the answer to the questions implied in man`s predicament are religious, whether open or hidden. Tillich says, “in systematic theology we must show the character of the existentialist revolt and confront the meaning of the existence which has developed in it with the religious symbols pointing to the human predicament.” In one word, existence is estrangement. It is not reconciliation. It is dehumanization and not the expression of essential humanity. It is the process in which man becomes a thing and ceases to be a person. Therefore, the state of existence is the state of estrangement. Man is estranged from the ground of his being, from other beings, and from himself. The transition from essence to existence results in personal guilt and universal tragedy. Man`s predicament is estrangement, but his estrangement is sin. It is not a state of things, like the laws of nature, but a matter of both personal freedom and universal destiny. Therefore we can call everything sin which does not result from faith, from the unity with God. Estrangement is separation; it is sin. Sin is conquered because estrangement is overcome by reunion in faith and love. The quest for the New Being is universal because the human predicament and its ambiguous conquest are universal. It appears in all religions. So, the New Being can be sought above history, and it can be understood as the aim of history. Tillich forms a clear definition of the New Being. “The New Being is essential being under the conditions of existence, conquering the gap between essence and existence.” The New Being is new in so far as it is the undistorted manifestation of essential being within and under the conditions of existence. It is new in two respects: it is new in contrast to the merely potential character of essential being; and it is new over against the estranged character of existential being. It is actual, conquering the estrangement of actual existence. To sum up, the New Being points to the power in Jesus as the Christ which conquers existential estrangement. That is to say, the New Being in Jesus as the Christ as the conquest of estrangement is the power in the picture of Jesus as the Christ. Therefore, if we can call Jesus as the Christ the New Being, we can say with Paul Tillich that the Christ is the power of salvation.