The founding of the Church of Jesus Christ of Latter-day Saints (LDS) and the role that religious fundamentalism played in killers Ron and Dan Lafferty's crimes are explored in Under the Banner of Heaven.

FX's true crime show recounts the murder of 24-year-old Brenda Wright Lafferty and her 15-month-old daughter Erica through the criminal investigation led by Detective Jeb Pyre (Andrew Garfield), a Mormon detective who struggles with his faith because of the horrific crime.

Alongside this, the drama also examines the life of LDS church founder Joseph Smith Jr. in juxtaposition with Wright Lafferty's experience with the Lafferty family after marrying the youngest son Allen, and particularly how Ron and Dan became obsessed with religious fundamentalist beliefs.

With so much of the story concerned with the Mormon faith, here is all you need to know about the LDS church's response to it.

Under the Banner of Heaven was created for the small screen by Dustin Lance Black, and the Oscar-winning scriptwriter was raised in a Mormon household.

The show is based on Jon Krakauer's nonfiction book of the same name, which Black told Newsweek he had been trying to adapt for 10 years because his original plan of adapting the story into a film proved too difficult.

Reflecting on how a two-hour runtime for a film would not suffice to tell the story he wanted, Black said: "It's not enough time to tell all of the Lafferty story from 1979 to 1984, all of the investigation story, that 10 days it took to solve this crime, and the Mormon history that helps us understand both of those stories.

"I needed all of that to, in a way, create an experience that [is] reminiscent of the readers' experience with Jon Krakauer, [with] his book."

The LDS church has not commented on the Black's TV show, but it did release a lengthy statement about Krakauer's book in 2003.

In it, the church provided three different responses to the book and its depiction of Mormonism, all of them highly critical of how Krakauer had portrayed the religion.

One response from the Church's then Director of Media Relations Mike Otterson stated that the book does a "huge disservice" to its readers by relying on stereotypes.

In his statement, Otterson said: "Krakauer's portrayal of The Church of Jesus Christ of Latter-day Saints is utterly at odds with what I—and millions like me—have come to know of the Church, its goodness, and the decency of its people.

"This book is an attempt to tell the story of the so-called fundamentalist or polygamous groups in Utah, and to tie their beliefs to the doctrines and the history of The Church of Jesus Christ of Latter-day Saints. The result is a full-frontal assault on the veracity of the modern Church."

A review of the book by Robert L. Millet, then a professor of religious understanding at Brigham Young University, went into great detail to critique and correct aspects of Krakauer's book, such as what he wrote about plural marriage.

In conclusion, and referencing quotes from the book, Millet said: "'Under the Banner of Heaven' is not only a slap in the face of modern Latter-day Saints but also a misrepresentation of religion in general.

"It is an insult to those 'unreasonable' beings out there who rely upon the 'murky sectors of the heart and head that prompt most of us to believe in God—and compel an impassioned few, predictably, to carry that irrational belief to its logical end'.

"We should not be surprised that an author who begins his work with the statement that 'faith is the very antithesis of reason' should thereafter proceed to grossly stereotype and thereby marginalize Mormonism."

Newsweek has contacted the LDS church for comment on the FX show's depiction of the Mormon faith.

Under the Banner of Heaven airs Thursdays on Hulu.

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