because of the individualistic standpoint which they adopt, it is difficult to class together the representative writers who contributed to the literature of english deism as forming any one definite school, or to group together the positive teachings contained in their writings as any one systematic expression of a concordant philosophy. there is no central authority that defines deist beliefs and practices, thus deists vary considerably in their beliefs. many of them were materialistic in their doctrines; while the french thinkers who subsequently built upon the foundations laid by the english deists were almost exclusively so. others rested content with a criticism of ecclesiastical authority in teaching the inspiration of the sacred scriptures, or the fact of an external revelation of supernatural truth given by god to man. deism inevitably undermined the personal religion of the judeo-christian tradition. "since the beginning the christian faith has been challenged by responses to the question of origins that differ from its own...some admit that the world was made by god, but as by a watch-maker who, once he has made a watch, abandons it to itself (deism)."