SALT LAKE CITY, June 29 (Reuters) - Troubled by issues ranging from polygamy to gay marriage, several dozen Mormons plan to resign this weekend from the church en masse in an unusual public show of defiance in Salt Lake City.

Organizers say participants in Saturday's mass resignation will gather in a public park to sign a "Declaration of Independence from Mormonism," followed by a hike up Ensign Peak, scaled in 1847 by then-church President Brigham Young to survey the spot where his Latter-day Saints would build a city.

The planned rally marks an unusually display of defiance from members of the Utah-based Church of Jesus Christ of Latter-day Saints, known for its culture of obedience. But the restive Mormons say they mean no disrespect.

"We're not doing it out of anger, and we're not doing it to poke a finger at the church," said organizer Zilpha Larsen, 36, a lifetime Mormon who has not attended church since 2005. "We're doing it to support each other in this decision that's going to cause pain for our families, which will cause pain for ourselves."

Mormonism bills itself as the one "true" Christian faith, and its theology promises families eternal relationships among those who remain faithful, sealing those gifts through special religious rites. Those bonds are deemed nullified when one's membership is revoked or resigned, said Larsen, who lives in Lehi, Utah, and has not baptized her two children.

In addition, Mormon culture often stigmatizes those who fall away, leaving some without social or business connections. Such consequences are widely documented on the Internet through blogs and websites such as exmormon.org, post-mormon.org and podcasts like those posted at mormonexpression.org, which is run by Larsen's husband, John Larsen.

REASONS FOR RESIGNATION

Among the reasons cited by those resigning are the church's political activism against gay marriage; doctrinal teachings that conflict with scientific findings or are perceived as racist or sexist; and inconsistencies in the church's explanation of its own history, including the practice of polygamy.

The church, which renounced plural marriage over a century ago as Utah was seeking statehood, often downplays the prevalence of the practice by early faith leaders, including Smith, who some scholars say was married to more than 30 women.

But it was in fact polygamy that John Larsen said began him on his journey out of the church. When doing research on the Larsen family tree, he was disturbed to find that a female ancestor had married Smith, likely while she was still married to another man, he said.

Zilpha Larsen said her questions began when she discovered that the veracity of an allegedly accurate translation of ancient Egyptian writings that were included in sacred Mormon texts were in doubt. "Once you start doubting one thing, then everything becomes suspect," she said.

More than 100 people have contacted the Larsens about joining the resignation event, the couple said.

Some have said they no longer wish to be counted in the church's annual reported membership data when they no longer believe, Zilpha Larsen said. "I don't want to make it seem like they have more supporters than they do," she said.

Many Mormons who find themselves questioning their faith try a cafeteria-style approach to remaining in the church, embracing those aspects of Mormon life that work for them and ignoring the rest. Even when such an approach fails, Larsen said, lapsed Mormons commonly stop attending church but leave their names on the rolls to avoid the social consequences.

"It's not like any other religion in America, like being a Protestant ... it's more tribal," Larsen said. "We know so many who feel so afraid to resign ... they feel trapped."

Saturday's event was organized in part as a means of sparking a dialogue about the emotional and social costs suffered by those who resign, the Larsens said.

"The point is to encourage a healthy transition and reduce the costs of leaving," John Larsen said.

PRIVATE STATISTICS

Figures released by the church in April claim 14.4 million members worldwide. The number of those resigning from the church are not publicly reported, nor does the church publicly estimate what percentage of members actively participate in the church.

Church spokesman Michael Purdy, responding to an email from Reuters, did not directly answer questions about resignation rates or the planned resignation event.

"We love and respect every member of the Church. People make their own decisions about the direction they will follow in life," Purdy said in a statement. "While there are very few who take this action, it is sad to see someone choose to leave. We wish them well."

According to the 2010 version of the "Church Handbook of Instruction" posted on the Internet, those wishing to resign their membership must submit a letter requesting that their name be removed form church records.

The handbook requires bishops, the lay leaders assigned to supervise congregations, to verify that the requester understand the consequences, specifically that resignation cancels "the effects of baptism and confirmation, withdraws the priesthood held by a male member and revokes temple blessings," the handbook states.

Resignation letters will be collected at the rally and mailed following the event, Zilpha Larsen said. (Editing by Steve Gorman and Philip Barbara)