Nearly every page of the book describes sulfur-breathing, black-winged, slobbering demons battling with tall, handsome, angelic warriors on a level of reality that is just beyond the senses. However, Christian believers and New Age demon-worshippers are able to influence unseen clashes between good and evil by the power of prayer. Peretti's violent descriptions of exorcisms are especially vivid: "There were fifteen [demons], packed into Carmen's body like crawling, superimposed maggots, boiling, writhing, a tangle of hideous arms, legs, talons, and heads."
Hmmm. Sounds like the movie Constantine, which we actually enjoyed very much!
We enjoyed Constantine, also. I read TPD and the sequel many, many years ago and enjoyed them. They were clever and entertaining and more uplifting than Constantine.