It is widely acknowledged that the history of Western society is characterized above all by the rise and spread of a socio-economic rationalization and its concomitant ideological manifestation, cultural rationalism. In theological circles, it has become something of a commonplace to affirm that the contemporary theological agenda is shaped decisively by this ‘rationalistic’ post-Renaissance and post-Enlightenment intellectual setting. In the same theological circles, it is also widely believed that of the significant theologians of this century, none tried harder or more rigorously than Dietrich Bonhoeffer to face up to the implications, for theology, of the ‘disenchantment’ of the world associated with the rise and growth of social rationalization and cultural rationalism. It is hard to gainsay that Bonhoeffer's greatness as a theologian lies in the freshness and intellectual vigour he brought to the task of understanding what would be involved, theologically, in facing the central tenets of the Christian faith up to a world that is (allegedly) ‘religionless’. My purpose in this essay is five-fold. Firstly, to use some of Max Weber's ideas to chart the course of the world's progressive ‘disenchantment’. Secondly, to evaluate Bonhoeffer's proposals for a properly-constituted theological response to the essentially ‘this-worldly’ intellectual horizon brought about by the ‘disenchantment’ of the world. Thirdly, to argue that Bonhoeffer's proposals, which centre on this notion of the ‘discipline of the secret’ (Arkandisziplin), are rendered problematic by a dialectic inherent in the processes of social rationalization.