(RNS) —  In the summer of 2008, leaders in The Church of Jesus Christ of Latter-day Saints drew a line in the sand against same-sex marriage, urging Mormons in California to do all they could to support Proposition 8, a referendum that would restrict marriage to heterosexual couples in the state via a constitutional amendment.

“Our best efforts are required to preserve the sacred institution of marriage,” the church’s First Presidency wrote in a letter read to all California Latter-day Saint congregations that June.

Voters narrowly approved Proposition 8, but the church’s public image took a beating, said Benjamin Park, a scholar of Mormonism at Sam Houston State University. “Church leaders recognized the writing on the wall,” said Park.

The church’s public image took a beating, said Benjamin Park, a scholar of Mormonism at Sam Houston State University. “Church leaders recognized the writing on the wall,” said Park.  

The defeat led LDS leaders to back the Respect for Marriage Act, a bill that would protect same-sex marriage that Congress is now expected to pass this week with bipartisan support. In Wednesday’s 62-37 vote in the U.S. Senate to end debate on the bill and advance it, Republican Sen. Mitt Romney of Utah was among the yeas.

Benjamin Park. Courtesy photo

The LDS’ backing of the bill, which came as a surprise to many who haven’t followed the church’s history, didn’t stem from their disappointment over Prop 8 alone. After the Prop 8 fiasco, church leaders converted to a strategy of compromise on LGBTQ rights, at least in the public square, said Park. They saw that expanding rights for same-sex couples could also provide protection for religious groups.

That realization eventually led to the so-called Utah compromise of 2015, in which LDS leaders backed an anti-discrimination law to protect LGBTQ people in Utah that carved out religious liberty protections.

The current bill, Latter-day Saint leaders said, also guarantees the rights of both LGTBQ Americans and religious groups with more traditional views of marriage.

“We believe this approach is the way forward,” church leaders said in a statement Tuesday (Nov. 15). “As we work together to preserve the principles and practices of religious freedom together with the rights of LGBTQ individuals, much can be accomplished to heal relationships and foster greater understanding.”

Park said the Latter-day Saints realized that their support for nondiscrimination creates the social capital needed to protect the rights of churches to govern their own affairs. 

Other religious leaders who believe that same-sex marriage is sinful took a different approach.

Catholic bishops have labeled the Respect for Marriage Act a threat to both marriage and religious liberty and claimed in a letter this past summer that it could open the door to legalizing polygamy.

RELATED: The Respect for Marriage Act protects my family — and my faith

Writing on Facebook on Tuesday, evangelical leader Franklin Graham mocked the proposed law as the “Destruction of Marriage Act,” while approving of an article by Southern Baptist Theological Seminary President Al Mohler that called the bill a threat to religious liberty and to conservative values.

“Anyone who would redefine marriage, the most fundamental building block of society, is no conservative, no friend of the natural family, and no defender of family values,” Mohler wrote at World Opinions, a conservative site where he serves as editor.

The Respect for Marriage bill, introduced this summer, gained traction this week after a group of U.S. senators proposed an amendment adding protections for religious liberty and banning polygamy. The law also protects interracial marriage.

Patrick Mason. Photo courtesy of Utah State University

“I guarantee the church was happy that polygamy is not protected,” said Patrick Mason, a professor of LDS history at Utah State University. “The church does not want to touch polygamy with a 10-foot pole.”

Latter-day Saints gave up polygamy in the 1800s because church leaders realized that keeping plural marriage as a religious practice threatened the church’s survival, Mason pointed out. He said that while revelation from God might have played a role in giving up polygamy, there was a pragmatic side as well.

“Church leaders realized that the necessary thing they had to do was protect the right to retain their temples, perform their sacred ordinances, and send missionaries in the world,” he said. “Everything else was negotiable.”

That kind of pragmatism has stuck with church leaders, said Mason. In some ways, he added, Latter-day Saints know that being a faithful citizen means being a good loser.

But the Prop 8 fight had at least as much impact on the church’s attitude toward this week’s vote. Troy Williams, executive director of Equality Utah, said the episode actually forged a closer relationship between marriage equality activists in Utah and Latter-day Saint leaders.

RELATED: New memoir unpacks what Mormon girls are taught about marriage

When supporters of marriage equality learned in 2008 that money was flowing from Utah to California, they reached out to church leaders to see if the two sides could find common ground, said Williams.

Those early meetings were tense but eventually led the church to support for local anti-discrimination laws and then for a statewide compromise drawn from similar laws in California and New York, which have long carved out exemptions for religious groups. “It’s not like we invented something new,” Williams said.

He said marriage equality activists in Utah wanted to change public policy, not church doctrine.

L. Tom Perry, second in line for the LDS church’s presidency, left, shakes hands with Troy Williams, executive director of the gay rights group Equality Utah, after a news conference at the Utah Capitol on March 4, 2015. Photo by Francisco Kjolseth/The Salt Lake Tribune

“That’s not up to us,” he said. “That’s between church members and their leaders. The key to living in a pluralistic society is that we have to be able to figure out how to coexist and respect people where they are.”

The willingness to compromise has helped change public opinion about marriage for same-sex couples in Utah, said Williams, pointing to a recent survey, published by the LDS-church-owned Deseret News, that found that 72% of the state’s residents support same-sex marriage.

A similar poll in 2014, according to the Deseret News, found that 57% of Utah residents opposed same-sex marriage.

“What happened is that people started going to their children’s same-sex weddings and having a blast,” said Williams. “And they saw the love and joy in their children’s hearts. That’s what has truly shifted in this moment.”

Williams sees the hoped-for passage of the Respect for Marriage bill as a sign that same-sex marriage, once a polarizing issue, can bring Americans together.

“We all need a success story right now,” he said.

Robin Fretwell Wilson, a University of Illinois law professor who helped craft the Utah compromise, agrees. Wilson has long argued that same-sex marriage supporters and religious groups can work together and has advocated for the so-called Fairness for All bill, a stalled piece of federal legislation modeled on the Utah compromise.

Wilson has described civil rights — such as same-sex marriage and religious liberty — as “puzzle pieces” that can fit together if people of good faith work together.

She said the apocalyptic thinking that fueled much of the opposition to same-sex marriage has largely disappeared.

“It was panic, panic, panic — and then it was gone.” 

RELATED: Study: Americans overwhelmingly support LGBTQ nondiscrimination laws