The High Middle Ages had taught that Christians were involved in an exalted but highly complex, hierarchically-organized pilgrimage to God. Obstacles to completion of that pilgrimage came from all segments of Christendom. Dr. Rao explains that the Second Council of Lyon in the late 1200s was designed to tackle all of these obstacles, from that of Christian disunity and the failure of the Crusades to practical parochial vices.