The main theme of the book “Lucifer” by the famous Protestant philosopher J.B. Russell is the development of the historical concept of the devil in various civilizations, which is studied using the comparative method, which allows us to trace how conceptual evil is personified through various refractions of its negative essence.B The book examines medieval teachings about the devil that arose in the Orthodox East, Catholic West and the Islamic world. Since demonology is framed in a clear structure in the Middle Ages, special emphasis is placed on the medieval tradition, which absorbed dogmatism and mysticism as two components of the concept of the devil. The author tries to identify various aspects of the manifestation of personified evil, analyzing not only its dogmatic and canonical definitions, but also raising a huge layer of folk legends recorded in the folklore of various peoples of Europe and Asia. Medieval folklore directly expresses the depth of human experiences and fears during a personal encounter with evil.