 German philosophers at the time were spreading the importance of a vassal to share the religion of their lord.The Inquisition may have just been the result of putting these ideas into practice.The use of religion as a unifying factor across a land that was allowed to stay diverse and maintain different laws in other respects, and the creation of the Inquisition to enforce laws across it, maintain said religious unity and control the local elites were consistent with most of those teachings.