From the time of Charlemagne (800-814) and beyond, all the peoples of Europe worshipped the one spiritual God according to the teachings and practice of the Roman Church. Christendom comprised a gradually expanding feudal organization of various tribes and ethnic groups in western and central Europe. All professed the same Faith as the common heritage of noble and peasant alike. This unity of Faith and feudal organization was held to be the cornerstone of the stability of society itself. So deep and abiding was this consensus that any deviation from the common faith was felt to be a serious threat to the community itself and hence at times resulted in mob violence…So iniquitous were heresies considered to be that the first violent reactions came not from the authorities ecclesiastical or civil, but from the populace themselves.
Albert Shannon, The Medieval Inquisition