Dr. John Rao explains that Nominalist, millenarian, and apocalyptic heresies continued to abound in the 1400's. These were aided by the corruption of the Church and her hierarchy. Bishops and priests often did not teach or even administer the sacraments. Much corruption had become so ingrained that it was actually treated as "traditional", so that efforts to remove it could be chastised as anti-Catholic! The hunt for raw political power on the part of the so-called "new monarchies" also contributed to poisoning the atmosphere by the end of the 1400's. Taken from: Christianity in the Late Middle Ages-Early Renaissance - 1996 VonHildebrand Institute