This important study brings to light a little known but essential moment in the relations between Islam and Christianity: the history of the 1542 publication of the Quaran (Koran), in Latin, in Venice and Basel and the controversy surrounding the emergence of this work in religious reform circles. This research relates the origins of European attitudes of tolerance to the Reformation and the reformers specific interest in non traditional religious theology and secular philosophy. The Koran proved to be a major though overlooked element in this movement toward cultural heterodoxy. (TEXT IN FRENCH WITH ENGLISH SUMMARIES)