The Mormon Church has deemed married same-sex couples to be apostates of the faith and their children ineligible for baptism in a reaffirmation of opposition to gay marriage months after endorsing fair housing and employment on the basis of sexual orientation.
The new policy was approved by Mormon leaders - the Council of the First Presidency and Quorum of the Twelve Apostles - to instruct local clergy how to proceed in light of the U.S. Supreme Court's landmark ruling in June legalizing same-sex marriage and similar moves in other countries.
The Salt Lake City-based Church of Jesus Christ of Latter-day Saints, as the Mormon faith is formally known, claims more than 15 million members and 85,000 missionaries worldwide.
Mormon officials said church doctrine has long regarded marriage as a union solely reserved for a man and a woman. And while the church has staunchly opposed extending marriage rights to same-sex couples, it has welcomed celibate, single gay men and lesbians to the religion.
Under the policy approved on Thursday, same-sex marriage was added to the list of acts considered to be a renunciation of the Mormon faith and thus subject to church discipline, including excommunication.
The new policy also prohibits natural or adopted children of same-sex married couples from receiving a naming blessing or from being baptized or confirmed in the faith until they turn 18, leave their parents' home and personally disavow same-sex marriage or cohabitation.
The same conditions would apply to children of same-sex couples recommended for missionary service.
The move seemed at odds with the church earlier this year giving its support to legislation signed into law by Utah Governor Gary Herbert in March barring discrimination in the workplace or housing on the basis of sexual orientation or gender identity.
"This is a difficult event to witness," the group Affirmation, an organization of lesbian, gay, bisexual and transgender Mormons, said in a statement. It said its leaders had "received a flood or reactions from LGBT Mormons, and family members and friends including grief, shock, disbelief and spiritual confusion."
Troy Williams, executive director of the gay rights group Equality Utah and a former member of the faith, said all churches have the right to welcome or exclude whomever they choose.
Still, he added, "We know that children of same-sex parents are treasures of infinite worth. In our universe, all God's children have a place in the choir."