Paul Tillich's Systematic Theology (three volumes, 1951, 1957, 1963) is the most ambitious systematic theological project produced in the Anglo-American world in the twentieth century and the work through which existentialist philosophy was most deeply integrated into Protestant theological thought. Tillich was a German Lutheran theologian who had been dismissed from his Frankfurt professorship by the Nazis in 1933 and emigrated to Union Theological Seminary in New York, where he became the dominant figure in mainline Protestant academic theology for a generation.
The system's methodological foundation is what Tillich called the 'method of correlation': theology's task is to analyze the existential questions that arise from the human condition - questions about finitude, anxiety, guilt, meaninglessness, and the threat of non-being - and to show how Christian symbols provide answering revelations. This is not apologetics in the conventional sense (arguing that Christianity is true) but hermeneutics (arguing that Christian symbols address the questions human existence raises). The method assumes that secular culture's deepest questions are implicitly theological, and that theology's deepest answers are implicitly existential.
John 1:14 - 'And the Word was made flesh, and dwelt among us' - grounds Tillich's central Christological concept: the 'New Being.' The Incarnation is the appearance in history of a being in whom the existential estrangement of human existence - the gap between what we are and what we ought to be, between our essential nature and our actual existence - has been healed. Jesus as the Christ is not primarily a moral exemplar or a miraculous wonder-worker but the 'New Being under the conditions of existence,' the one in whom essential humanity is actualized without being destroyed by the corrupting forces of existence.
2 Corinthians 5:17 - 'Therefore, if anyone is in Christ, he is a new creation. The old has passed away; behold, the new has come' - is Paul's language for what Tillich translates into existentialist terms: the new creation is the New Being, the overcoming of estrangement by the power of being-itself that Jesus embodies and communicates.
Romans 8:22 - 'For we know that the whole creation has been groaning together in the pains of childbirth until now' - provides the cosmic scope of Tillich's analysis of estrangement. Alienation is not merely individual or social but ontological: the whole created order is in a condition of estrangement from the ground of being from which it came.
Acts 17:28 - 'In him we live and move and have our being' - is the text that supports Tillich's most controversial theological claim: that God is not a being alongside other beings but 'Being-itself,' the ground and power of being in everything that exists. This is not pantheism (God is not identical with the world) but panentheism: the world is in God as God is in the world. The formulation draws on the mystical tradition, particularly Meister Eckhart, as well as on Heidegger's ontology.
Tillich's system was enormously influential in the 1950s and 1960s, particularly in mainline Protestant seminaries and university theology departments. His influence waned in the 1970s and 1980s as liberation theology, feminist theology, and narrative theology raised different questions, but his work remains essential reading in systematic theology curricula and his methodological contribution - the insistence that theology must engage the existential questions of its cultural moment - is widely acknowledged even by those who reject his specific answers.
Tillich's personal life - his multiple extramarital affairs, which his wife Hannah documented in her posthumous memoir From Time to Time (1973) - has complicated his legacy and raised questions about the relationship between his theology of grace and his personal conduct. The complications do not cancel the intellectual achievement, but they are part of the full picture of one of the twentieth century's most gifted and flawed theological minds.
Tillich's personal life - his multiple extramarital affairs, which his wife Hannah documented in her posthumous memoir From Time to Time (1973) - has complicated his legacy and raised questions about the relationship between his theology of grace and his personal conduct. The complications do not cancel the intellectual achievement, but they are part of the full picture of one of the twentieth century's most gifted and flawed theological minds. The question of whether a theologian's life should affect our reading of his theology is one that Tillich's case raises with particular force, and the lack of easy consensus about the answer suggests that it is genuinely difficult.
The Systematic Theology's lasting significance lies not in the specific answers it gives - many of which have been revised or rejected by subsequent theologians - but in the questions it presses with unusual philosophical sophistication: What does it mean to say that God exists? How does the Christian claim that Jesus is the Christ address the existential condition of human beings alienated from their essential nature? What is the relationship between the Christian gospel and the deepest questions that secular culture raises? These questions remain urgent, and Tillich's engagement with them, whatever its limitations, remains a model of the kind of thinking that takes both theology and culture seriously.