Council of Tours

October 1, 1163

Alexander III convened seventeen cardinals and more than a hundred bishops at Tours to reaffirm his legitimacy against the imperial antipope and to condemn the Cathar heresy spreading through Languedoc. It marked the first formal church action against the Cathars. The council's denunciation signaled that Rome viewed dualist heresy as a structural threat to Christian society, not merely a local aberration that could be handled by diocesan authority.