21 Twentieth-Century Barth and Brunner Discuss Theological Method with Nineteenth-Century Liberal Schleiermacher Setting Once again it is necessary to use the literary device of purgatory, a training place for paradise, or heaven, to bring our theologians into conversation with one another. You’ve already met Schleiermacher in an earlier imaginary conversation (19). He was the reputed father of modern Christian theology and the father of liberal Protestant theology. Karl Barth was born in Switzerland