What is the scariest book you've ever read?

[Irving]

prob. The Exorcist

I read Legion by the same author. It has some of the same characters, and references stuff that happens in the Exorcist. I've only seen the movie of the Exorcist, I may have to read the book of that as well.

Legion is a pretty cool book and has what I would consider a pretty high level of interesting religious perspective in it, without coming across preachy at all.