Faith as a door is a fascinating image. A new horizon appears at precisely the moment when a man decides to cross the threshold and look out at the reality that is beyond his doorstep. Yet, faith turns out to be an absurdity in today's post-Christian society. Reason would no longer be able to furnish us with certainties, such as the foundational role of truth to undertake the study of any discipline. Consequently, God is nonsensical. But while reason has seen its oblivion, there is however an attempt, in a dominant relativism, to overcome the role of reason with love. Love would mean and do more than truth. Love without truth-namely without its bond with reason- is empty, a mere sentiment, as, on the contrary, truth without love is a cold system of causality. Reason and love have rather to go hand in hand. Their circularity on a natural level, which includes the harmonic relation between intellect and will, is the condition for faith and charity to work out their indispensable complementarity. The paradigm "reason and love" is then propaedeutic to verifying for instance the correct relationship between doctrine and pastoral care or to showing how dangerous it is to ignore it. Bad effects of a denied encounter between reason and love can be seen in religious fundamentalisms or in a religious freedom that easily prefers social religious stability to the priority of the true God and true religion.