Theologian Karl Barth, in about 1930. After reading Bonhoeffer’s doctoral dissertation, The Communion of Saints, Barth declared it “a theological miracle.” Bonhoeffer studied theology at the great liberal faculties of Tübingen and Berlin. At the University of Berlin, he was especially stimulated by his study of Martin Luther. But the greatest theological influence on Bonhoeffer came from the writings of a Swiss theologian who was then teaching in Germany—Karl Barth. Bonhoeffer never studied with