What metaphors are used in The Descent: A Novel by Jeff Long?

The Shroud of Turin is a metaphor for Christian belief. The Shroud of Turin is an ancient cloth that is believed to have been the cloth that was wrapped around Jesus upon his death from crucifixion. The cloth is said to have the image of Jesus on it. de l'Orme proves to the Beowulf Circle in this novel that the image on the cloth was made with primitive photographic techniques and that the image on it is that of the devil. de l'Orme claims that the devil has done this in a manner of manipulation, to cause people to believe in Jesus so that they might also believe in the devil.