This paper provides a theoretical discussion of the role the introduction of writing plays in the development of religious conceptual systems. It is argued that the writing down of religious traditions makes the transmission of radically counter-intuitive ideas possible, and that the formation of Canons introduces the distinction between a foundational text and its philosophical commentary. Defending the foundational role of the sacred texts by rational argumentation either leads to endless regression of arguments, or to circular reasoning and paradoxes. To accept this as natural, would deprive sacred texts of their special status as the foundation. In religions, this deadlock is used to illustrate the limits of human reasoning powers and, by the same token, to prove that there must be an ultimate reality which can only be accessed through "revelation", "enlightenment", and the like.