This book is filled with engaging characters and memorable, significant action scenes. The themes are serious and it treats them seriously, but there are moments where the somberness is broken not by levity but by hints of grace coming from above, like a sunbeam breaking through the clouds.
The plot builds to a page-turning rush of action that never lets up (well, eventually the book ends...but not till shortly before that). Some reviewers have remarked the first part of the book was slower; it is, but I didn't have any problem with it: Newquist does a great job setting out the background with intriguing storytelling even before you get to the zombies and vampires and...oh, just read it.
Since it's listed on Amazon with the subtitle (or whatever you call it) The Prodigal Son Book 1, I don't think I spoil anything by mentioning that the end leaves room for a sequel or two, or several, and I'm hoping those will be forthcoming. It's excellent reading.