Deeply disappointing; it blurbs itself as 'A novel of the war between science and superstition', but the unsubtly-plumped Good Guys of science don't use science at all, or even reason, really. They depend on a magical mcguffin artifact made by a supernatural big daddy, and occasional paladins born with the ability to wield it, and yer general narrativium of suffering nobly and therefore winning. The unspeakable forces of evil, on the other hand, not only use physics but combine it with reality; and they are also better at psychology and politics.
Another blurb says 'will ... outrage true believers -- of all stripes'; the story goes on to posit that there is good Christianity, which is still a matter of dangerous belief but was invented by the good demon to spike evil Christianity. There is nothing carefully thought through in this entire plot, and I don't think it could outrage anyone more conventional than .
Do not find in a library.
So wrote clew in SF&F.