Johannes Corrodi Katzenstein offers a contribution to the current debate on Kierkegaard, mostly concerning the rationality of religious belief and the presumed religious neutrality (autonomy) of philosophical and scientific thought. More specifically, his book is an attempt to relate Kierkegaard's theory of the stages of life (aesthetic, ethical, religious) to issues that have been of utmost concern to Anglo-American (analytical) philosophy, such as the nature of truth, rational knowledge, objectivity, etc. From this angle, Kierkegaard turns out to be not the irrationalist he has often been made into but rather the outspoken witness of a passion that guides all thinking, i.e. the passion to think what cannot be thought. An attempt is made to show that for Kierkegaard, anticipating some of the arguments of contemporary postsecular philosophy, the ideal of pure or autonomous reason inevitably has its basis in a pre-rational, often tacit commitment to an origin whose primary home is in religious faith. Rather than precluding dialogue, awareness of these deeper forces and starting-points of our various philosophical and scientific outlooks is a critical requirement for mutual understanding between secularist and religious perspectives and traditions competing for cultural and political dominance.