This is the first book I've read of yours. The other books are more traditional fantasy with different worlds and stronger themes of magic. This is much different. It's a new take on how magic might be a part of the present world. It might be there even if we don't see it.
Writers use small towns and kids as a kind of microcosm of the larger world.
When you're writing about a small scale, frequently you're talking about a larger scale. This book is in a small space and with few characters, but I think it is still representative of the world at large. I think that's why it works. First of all, God is not throughout Demon . The mention is almost solely confined to the word and the void.