I received a free copy of this book from Waterbrook Multnomah's Blogging for Books program.
I want to deal with this book from two angles, story and theology.
Story—It has an interesting premise, that the results of an experiment causes the hero of the story to see things that no one else can see, and how this young man acts and reacts to the things he's seeing that no one else can see. The story keeps up a fairly good pace, and kept my interest.
A bit on the down side, while the main characters were likeable, they were not always all that believable. While many of Drew's actions made sense, I still got the impression that things became too The Matrix-like with his super-fast reaction times and how he came to use them. Perhaps because we see things mostly from Drew's eyes (it's not a first-person story, but still told from his perspective), Sydney sometimes comes off as too perfect, always doing the right things for all the right reasons.
The “invaders” are an interesting take on the whole angels and demons thing, if one keeps in mind that it is only the author's speculations. One good thing the author did was to factor in Drew's and Berg's ignorance about things spiritual and religious, so for them the “invaders” are not angels, but other kinds of beings.
Theology—Spiritual warfare is a big thing in a lot of churches and movements, and the teachings about it can be rather bizarre. While I'm trying to keep in mind that this is a work of speculative fiction, there are some aspects of what happens in this story concerning the spiritual warfare that happens in it that did cause me to wonder.
For example, why were the evil invaders (demons) unable to follow Drew when he took a boat out on the water? And why did it seem like even a good invader (angel) was hurt when rain fell on him? Maybe it was only a device for the story, but it's an odd one. Following that logic, one would think that a submarine would be completely demon- and angel-free. I don't recall any such thing being taught in the Bible, either.
In another part, the story's main battle towards the end, the good invaders (angels) are empowered when Sydney seems to be praying. This is a fairly popular teaching in some circles, that our prayers empower angels or free them to do things or keep them employed, but even the author, in the study guide at the end of the book, notes that the Bible doesn't teach that this is how prayer works.
So, on the one hand, I enjoyed the book as a story. It was a quick read, and kept my interest. Perhaps that is how it should be read, as speculative fiction, as simply a fairly good Christian sci-fi thriller. But one should be wary of reading it as an example of spiritual warfare, or as a glimpse into how angels and demons fight each other.