In 1984, Ron and Dan Lafferty walked into their younger brother's house and their sister-in-law Brenda and her 14-month-old daughter in cold blood. For their entire lives, neither expressed guilt for their crime because God had told them to do it. Jon Krakauer takes you into the world of Mormon fundamentalists, radical break-offs of the mainstream Church of Jesus Christ of Latter-day Saints. In between showcasing various fundamentalist groups, Krakauer explains the early teachings of the church that such people take to the extreme to justify polygamy and violence in the name of God. 

I could not put down this fascinating look at the extremist offshoots of Mormonism. Being an agnostic, Krakauer's skepticism of religion is heavily on display. Yet, I found it fascinating to contemplate his views on the rationality of religion. Is a religious fanatic sane? And if not, can he be tried for his crimes? Any belief taken to an extreme can lead to violence. In Under the Banner of Heaven, Krakauer focuses on fundamentalism in Mormonism, but the same principle could be written about plenty of different beliefs.