One of the most frequent assertions by Jesus myth theorists is that the Gospel is based on Egyptian mythology. The reason for this is that Egypt is both really familiar and unfamiliar. That is, we are very aware of certain aspects of ancient Egypt but quite ignorant of the details. For this reason it is helpful for Christians to become more aware of ancient Egypt. A good place to start is Max Muller’s Egyptian Mythology. This is an older book but it still gives a very good overview of the issues and the characters of Egyptian mythology. In particular, Muller exposes the myth that there was ever a place for monotheism in ancient Egyptian religion. The book also includes many sections from the original texts and quite a few diagrams.
