Lucifer, The Devil in the Middle Ages is both a scholarly assessment of the development of diabology in the Middle Ages and an impassioned plea to the 20th century to recognize and acknowledge the existence of real, objective evil. The third in a series of works tracing the history of the devil from his Judeo-Christian roots, it represents a formidable undertaking; the devil's history is integrally related to the problem of evil, which is in turn at the heart of Western religious thought.