Demonology is not just another crackpot-ology. ... Thousands of books have been written on the subject, ... The manifestations and occurrences described in this imposing literature are similar, if not entirely identical, to the UFO phenomenon itself. p. 215.
The Devil and his demons can, according to the literature, manifest themselves in almost any form and can physically imitate anything from angels to horrifying monsters with glowing eyes. Strange objects and entities materialize and dematerialize in these stories, just as the UFOs and their splendid occupants appear and disappear, walk through walls, and perform other supernatural feats. p. 216.
Just today I was talking with someone about demons and religions and spirituality...how demons and the Satan myth are variations on the concept of not only negative energies and entities, but "soul eaters" which, some UFO researchers theorize, the "grays" are.