Frank Peretti wrote some books in the late 80s maybe early 90s.

The 2nd book is called Piercing the darkness, and listening to it now, I'm blown away by how much of what they're talking about has actually happened in America, and how schools have been influenced.

It's a Christian book that shows the angelic and demonic realm working on the humans.

If you haven't read it, but want a good story that might make you think, I highly recommend it!