The Big 5: Books that Changed Your Mind

You have beliefs, doctrinal convictions, mission convictions, and much more.  Some of those are different than what they used to be.  Maybe someone helped to change your mind.  At times there's a book that challenged us and helped to change our minds.

What are your Big 5 books that changed your mind?

This won't work unless you give us a phrase or two on what actually changed about your thinking, beliefs, doctrines, whatever.  You may not have 5, and that's fine.  Oh, and if you want to cheat and use a book of the Bible, I'll let that slide here.  Please only do that once, though.