His thought is broad and complex. He, like Bultmann, was heavily influenced by K. Tillich said that theology must concern itself both with Christian truth and the human situation. The theologian stands within the community of faith and attempts to understand the situation and the human existential questions that arise. Then seeks to demonstrate that the symbols used in the Christian message are the answers to these questions. This is a philosophical description of the Biblical God and Tillich is attempting to reconcile the God of Abraham with the God of philosophy.
Sin is estrangement.
Tillich is at his existential best in describing human sin. The Fall symbolizes this universal reality, and the individual acts of sin point to its ontological foundation. The existential question, the anxiety and the alienation that exist are rooted in this reality. The work of the theologian is point to the symbols. The language of theology is symbol.