One of my favorite books by Stephanie S. Tolan, A Good Courage is a book revolving around a kid who spent his years up until adolescence hopping from one cult to the next (thanks to his mother, that is). One specific cult, an extremist sect of Christians, govern themselves with harsh punishments and outdated concepts and theories. While his mother finds it appealing, the kid finds his own safety in jeopardy he realizes that the harsh treatment of the children there can only result to death.
I'll be a little honest, you could learn the same lesson in a history book, but it shows how radical the changes were from today's society and back then, when people were deprived of knowledge and were ignorant enough to label accidents and misfortune as "God's Will". It was an eye-opener for me when I was a lot younger, when I hadn't seen this side of Christianity before.
