For a long time famous thinkers (such as Hegel or Marx, Auguste Comte or Max Weber) identified the Enlightenment with the critique of religion. Yet between Enlightenment and religion there has not only been a relation of opposition. A more attentive examination of the question reveals the presence of an "aufklärische" component within religion itself. In order to hold such a thesis, the author distinguishes a chronological, a historical and a structural dimension of the concept of Enlightenment; he assumes - with Kant - the structural dimension, as he conceives of the Enlightenment as a reflexive and communicative process, which aims at rational autonomy, both at an individual and a political level. The roots of that process have also been nourished by the duty to freedom and truth cultivated by Christian theology.