Paul Tillich (1886–1965) was born and raised in Germany. He received his PhD in 1910 and in 1912 was ordained in the ministry. From 1914 to 1918 he served as a chaplain in the First World War. Returning from the war, he taught both philosophy and theology at several universities. In 1933 the Nazi government suspended Tillich's position at the University of Frankfurt. He then went to the United States where, until 1937, he was Visiting Professor of Philosophy of Religion and Systematic Theology at Union Theological Seminary. He served at Union as Associate Professor of Philosophical Theology (1937–40) and Professor (1941–55). From 1955 to 1962, he was a University Professor at Harvard, and during his last three years he was the Nuveen Professor of Theology in the Divinity School of the University of Chicago. He was buried in New Harmony, Indiana. Tillich wrote a number of books among which are the following: Systematic Theology (3 vols, 1951–63), The Courage to Be (1952), Biblical Religion and the Search for Ultimate Reality (1955) and Dynamics of Faith (1957).

In his writings Tillich describes certain basic questions (he calls them ‘existential questions’) that arise out of the human situation. These questions cannot be answered within that situation. Their answers, he claims, are found in the great symbols of the Christian message. In his writings he endeavours to analyse the human situation and to interpret the traditional Christian symbols as answers to this situation.