How does the author present the theme of blood atonement?

Blood Atonement is an important theme in this book. In fact, it is this principle that the Lafferty brothers believe justify their murders of Brenda and Erica Lafferty. Like the principle of polygamy, however, this principle of blood atonement has also been disposed of by the modern Mormon Church. According to the principle of blood atonement those who had committed grievous crimes against the Mormon Church could justifiably be killed to avenge their wrongs. This doctrine was supported by both Joseph Smith and Brigham Young. The Mormons believed there were some sins so bad that they could not be forgiven or washed clean of their sins, even by the blood of Christ. Most Christian religions believe that there is no sin that cannot be forgiven by God if the sinner confesses and has his sin "washed" clean in the blood of Jesus. In the case of an unforgivable sin, the Mormons believe the only way to atone for their sin was to have their own blood shed.

Krakauer makes an interesting point during his description of the court session in which Ron is sentenced for his role in the deaths of Brenda and Erica Lafferty. In this session, the judge orders Ron put to death by shooting at the hands of a firing squad. Krakauer makes the point that Ron is condemned to the same punishment to which Brenda Lafferty is condemned by Ron. He is ordered dead because of the believed grievousness of his crimes. Krakauer writes that this sentence indicates that although the Mormons may have abandoned the principle of blood atonement, the United States Justice system has not.