What is the author's style in Under the Banner of Heaven: A Story of Violent Faith by Jon Krakauer?

Although it is uncertain if Krakauer is affiliated with the Mormons, it is obvious that he has done much research on the topic of their religion. It can be determined through the text that Krakauer has spent much time reading about the Mormon religion as well as talking with the Mormons themselves about their religion. Krakauer presents details of the historical development of the religion from its birth to modern times. He also describes how the fundamentalists, such as the Laffertys, have come to hold the beliefs that they hold as a result of their attempt to return to the root beliefs of their religion.