The chapter employs elements of the theology of Dietrich Bonhoeffer, especially the notion of religionless Christianity, for its potential to enhance an understanding of Islamic theological philosophies, medieval and modern, through drawing on helpful distinctions between religious institutionalism and faith. Examples of such philosophies include the works of Ibn Tufayl, Sayyid Qutb, and Mohamed Talbi. The terms of Husserlian transcendental phenomenology will be employed as central to the distinctions being drawn. Through the example that Bonhoeffer provides of countering the aberrant theological interpretations that underpinned Reich Christianity, so it is proposed that Tufayl, Qutb, and Talbi offer similar theological buttresses against aberrant interpretations to be found in Islam.