Jeff Green, a tech billionaire believed to be the richest man in Utah, has quit the Mormon church in protest in its stand on gay rights and equality.
Mr Green submitted his formal resignation to the church president, Russell Nelson.
In addition, Mr Green, whose wealth is estimated at $5 billion (£3.74 billion), has donated $600,000 to Equality Utah, an LGBT advocacy group.
The Church of Jesus Christ of Latter-day Saints – the formal name for the Mormon faith – has long opposed gay marriage.
In 2015 it changed its rules announcing that members in same-sex marriages face expulsion and their children would be barred from being baptised unless they disown their homosexual relationships.
However, the Mormons and Equality Utah also agreed on legislation known as the Utah Compromise which safeguarded religious freedom while protecting the LGBT community against discrimination in housing and employment.
The rule banning baptisms for children whose parents were in same-sex marriages was rescinded four years later.
But Mr Nelson insists that marriage should only be between a man and a woman.
Mr Green, the chairman and CEO of The Trade Desk, a technology marketing company, informally quit the church a decade ago.
The Salt Lake Temple in Salt Lake City
Credit: AP Photo/Rick Bowmer, File
However, he waited until Monday to make his decision official and ask the church to remove his name from the records, according to the Salt Lake Tribune.
Another 11 family members and a friend have followed suit.
Mr Nelson’s changes failed to satisfy Mr Green, whose letter of resignation represented a stinging rebuke to the Mormon church
“Although I have deep love for many Mormons and gratitude for many things that have come into my life through Mormonism, I have not considered myself a member for many years, and I’d like to make clear to you and others that I am not a member,” Mr Green wrote.
While most members “are good people trying to do right, I believe the church is actively and currently doing harm in the world. The church leadership is not honest about its history, its finances, and its advocacy,” he wrote.
“I believe the Mormon church has hindered global progress in women’s rights, civil rights and racial equality, and LGBTQ+ rights.”
Nearly half of Mr Green’s donation will go to LGBT students in Utah who may wish to leave Brigham Young University, which is sponsored by the Mormons.
The Mormon church did not immediately respond to a request for comment.