The German theologian and martyr Dietrich Bonhoeffer is not widely known for engaging with scientific thought, having been heavily influenced by Karl Barth's celebrated stance against natural theology. However, during the period of his maturing theology in prison Bonhoeffer read a significant scientific work, Carl Friedrich von Weizsäcker's The World View of Physics. From this he gained two major insights for his theological outlook. First, he realized that the notion of a “God of the gaps” is futile, not just in science but in other areas of human inquiry. Second, he felt that an infinite universe, as considered by science, would be self-subsistent and could exist as if there were no God. Bonhoeffer replaced Barth's radical critique of religion with the even more extreme view that it is a mere passing phase in history that grown-up humanity can dispense with. At the same time Bonhoeffer began an important critique of Barth's reaction, namely, the latter's retreat to a “positivism of revelation.” While Bonhoeffer did not go quite as far as one might like, his approach opened up hopeful avenues for an answer to “the liberal question” and even a revived place for some kind of natural theology.