Faith and reason are presently in crisis. This judgment, albeit controversial, constitutes the foundations of this book. The central danger of this crisis does not so much consist in the denial as in the banalization of God, whether as a fundamentally irrational claim of faith or at best as a purely regulative idea of reason. However, offering an account of the hope that is in us, and hence of the faith that gives rise to hope, requires on the part of Christian theology a rigorous intellectual effort, in short, the unfettered use of reason for the sake of faith in the God who is always greater than anything that can be thought. The purpose of this volume is to inquire into the reasons of faith in order to offer theological resources to address constructively the double crisis of faith in reason and reason in faith. First, it looks into the theological constitution of reason; second, into reason as one specific faculty of human being; third, into the significance of the philosophical shifts of modernity for theology; and fourth, into the importance of philosophy for theological inquiry.