Under the Banner of Heaven is a book written by Jon Krakauer. It is about the history of the Church of Jesus Christ of Latter-day Saints, also known as the LDS Church or the Mormon Church, and the ways in which religious extremism has led some members of the Church to commit violent acts.
The book explains that more than 150 years ago, a man named Joseph Smith founded the Mormon Church. He said that he was visited by an angel who gave him a set of golden plates that contained a new gospel, which he translated and published as the Book of Mormon.
Since then, many people have joined the Mormon Church and followed its teachings, which include strict rules about what to eat, drink, wear, and do. But some Mormons have taken these teachings to an extreme, leading them to commit violent acts.
For example, the book tells the story of two brothers, Ron and Dan Lafferty, who believed that God had commanded them to kill their sister-in-law and her baby daughter because they believed she was practicing witchcraft. They claimed that they were following God's will, but they were eventually convicted of murder and sentenced to life in prison.
Krakauer also explores the history of polygamy in the Mormon Church, which was a common practice in the early days of the Church but has been banned by the Church for more than a century. Some Mormons, however, still believe in polygamy and continue to practice it in secret.
Overall, Under the Banner of Heaven provides a detailed look at the history of the Mormon Church and the ways in which religious extremism can lead to violence.