German philosopher Karl Jaspers, Spanish philosopher Miguel de Unamuno, and Russian philosophers Nikolai Berdyaev and Lev Shestov. Karl Barth added to Kierkegaard's ideas the notion that existential despair leads an individual to an awareness of God's infinite nature. Russian author Fyodor Dostoevsky could be placed within the tradition of Christian existentialism. The roots of existentialism have been traced back as far as Augustine of Hippo. Some of the most striking passages in Pascal's Pensées, including the famous section on the Wager, deal with existentialist themes. Jacques Maritain, in Existence and the Existent: An Essay on Christian Existentialism, finds the core of true existentialism in the thought of Thomas Aquinas. Existential Theology In the monograph, Existential Theology: An Introduction (2020), Hue Woodson provides a constructive primer to the field and, he argues, thinkers that can be considered more broadly as engaging with existential theology, defining a French school including Gabriel Marcel, Jacques Maritain, and Jean-Luc Marion, a German school including Immanuel Kant, Johann Gottlieb Fichte, Friedrich Wilhelm Joseph Schelling, Georg Wilhelm Friedrich Hegel, and Dietrich Bonhoeffer, and a Russian school including Fyodor Dostoyevsky, Leo Tolstoy, and Nikolai Berdyaev. Radical Existential Christianity It has been claimed that Radical Existential Christians’ faith is based in their sensible and immediate and direct experience of God indwelling in human terms. It is suggested that individuals do not make or create their Christian existence; it does not come as a result of a decision one personally makes. The radical Protestants of the 17th century, for example Quakers may have been in some ways theo-philosophically aligned with radical existential Christianity. Further reading Cobb, John B. (1967). The Structure of Christian Existence(Philadelphia: The Westminster Press) Cochrane, Arthur (1956). The Existentialists and God (Dubuque: The University of Dubuque Press) Davis, George W. (1957). Existentialism and Theology: An Investigation of the Contribution of Rudolf Bultmann to Theological Thought (New York: Philosophical Library) Heinemann, F. H. (1958). Existentialism and the Modern Predicament (New York: Harper and Row) Jansen, G. M, A. (1966). An Existential Approach to Theology (Milwaukee: The Bruce Publishing Company) Jenkins, David. (1987). The Scope and Limits of John Macquarrie's Existential Theology (Stockholm: Uppsala) Kuitert, H. M. (1968). The Reality of Faith: A Way Between Protestant Orthodoxy and Existentialist Theology (Grand Rapids: Eerdmans) Macquarrie, John (1957). An Existentialist Theology: A Comparison of Heidegger and Bultmann (New York: The Macmillian Company) Martin, Bernard (1963). The Existentialist Theology of Paul Tillich