Under the Banner of Heaven: A Story of Violent Faith - Jon Krakauer

Krakauer shifts his focus from extremes of physical adventure to extremes of religious belief in this true story of an appalling double murder committed by two Mormon Fundamentalist brothers who insist God commanded them to kill.
This extraordinary work of investigative journalism takes readers inside America's isolated Mormon Fundamentalist communities, where some 40,000 people still practice polygamy. Defying both civil authorities and the Mormon establishment in Salt Lake City, the renegade leaders of these Taliban-like theocracies are zealots who answer only to God.

At the core of Krakauer's book are brothers Ron and Dan Lafferty, who insist they received a commandment from God to kill a blameless woman and her baby girl. Beginning with a meticulously researched account of this appalling double murder, Krakauer constructs a multi-layered, bone-chilling narrative of messianic delusion, polygamy, savage violence, and unyielding faith. Along the way he uncovers a shadowy offshoot of America's fastest growing religion, and raises provocative questions about the nature of religious belief.