"Credo ut intelligam" tells the story of the vicissitudes of Christian reflection in its tormented confrontation with Greek-Roman philosophy: a confrontation thanks to which Christianity developed new conceptual categories appropriate to its message of salvation. It is a speculative itinerary starting from the Gospels and ending with the dissolution of medieval Scholasticism; it spans 14 centuries, which are among the most interesting and fruitful in European culture. The author shows that the definition of "Christian philosophy" reserved for this phase of Western culture, is fully justified. In fact, it was Christian faith that then pushed theologians and philosophers to try to explain the contents of religion with the resources of reason. The book also makes it possible to make a useful comparison with non-Christian faiths and cultures and investigates - with reference to Islamic and Jewish thought - the other solutions historically given to the problem of the relationship between revealed content and rational reflection.