In 1898, B.H. Roberts, a high-ranking member of the Church of Jesus Christ of Latter Day Saints was elected to represent Utah in the House. At the time, Americans could grudgingly accept a Mormon politician as long as he wasn’t too Mormon. But Roberts still lived with the three wives he had married before the LDS church ended polygamy. Protestant ministerial associations and newspapers like the New York Evening Journal petitioned Congress to refuse Roberts his seat. The voices of rectitude delivered 7 million signatures written on 28 scrolls wrapped in the American flag to the Capitol. The House voted 268-50 against Roberts. His seat was given to a one-woman Mormon whose faith could be glossed over.

Over a century later, assertive Mormonism may find its political home in the conservative movement. The faith that once seemed like a threat to Christian values is increasingly viewed as an ally by social conservatives looking for recruits in the culture war. As Mormons have stepped forward to lead efforts against gay marriage, the enmity of liberals to the LDS church has increased. But evangelical hostility to Mormonism seems to be melting into acceptance, even admiration.

The “not-too Mormon” rule lingered from Roberts’s time to Mitt Romney’s recent presidential campaign, despite the impressive progress Mormons have made in politics. America’s 5.5 million Latter Day Saints make up just 1.6 percent of the population yet hold over 5 percent of congressional seats. Their ranks include Republican firebrand Jeff Flake and Democratic Senate Majority Leader Harry Reid. Church leaders like Ezra Taft Benson have served honorably in appointed office, and George W. Bush awarded LDS President Gordon B. Hinkley the Medal of Freedom.

But few elected officials have made Mormonism integral to their political identity—for good reason. Early in Romney’s campaign, USA Today reported, “as far back as 1967, only three quarters of Americans said they would vote for an otherwise well qualified person who was a Mormon. … Some 40 years later—the results to this question are almost exactly the same.” After Romney delivered his “Faith in America” speech addressing the Mormon question directly, Lawrence O’Donnell railed on “The McLaughlin Group,” “Romney comes from a religion that was founded by a criminal who was anti-American, pro-slavery, and a rapist!”

Though many religious conservative leaders hoped to endorse Romney, they found that a sizable portion of their flocks shared O’Donnell’s sentiments. James Dobson told talk-show host Laura Ingraham, “I don’t believe that conservative Christians will vote for a Mormon, but that remains to be seen, I guess.” Popular evangelical radio-preacher Bill Keller warned, “If you vote for Mitt Romney, you are voting for Satan!”

Romney’s campaign was derailed when Evangelicals turned to Baptist preacher-turned-politician, Mike Huckabee. His enthusiastic reception at the Values Voters conference prevented Dobson and other Religious Right leaders from endorsing Romney. Huckabee poked at Romney’s faith, asking a New York Times reporter, “Don’t Mormons believe that Jesus and the devil are brothers?” His strong showing among evangelical voters in the South doomed Romney’s bid.

But evangelical hostilities don’t last forever. When John F. Kennedy ran for president, many conservative evangelicals believed the Pope was the antichrist. The president of the National Association of Evangelicals warned, “Public opinion is changing in favor of the church of Rome. We dare not sit idly by—voiceless and voteless.” But two decades later, as Catholics took the lead in protesting abortion, evangelicals gradually traded theological rivalry for political co-operation. The alliance has become so natural that evangelicals were willing to reject co-religionist Harriet Miers as a nominee for the Supreme Court in favor of the more qualified Catholic Samuel Alito.

The same process of assimilation into the social conservative movement may be taking place for Mormons. Soon after the California Supreme Court declared same-sex marriage constitutional, Catholic Bishop of San Francisco George Niederauer asked the LDS church to join a multifaith coalition against gay marriage. By June, Elder Lance Wickman, a top LDS official, called Prop 8 “The Gettysburg of the culture war.” Church members fell in line, ready for a fight.

The LDS church rarely involves itself directly in politics, and its effort in California’s “Protect Marriage Coalition” represented a shift in church policy. In a satellite simulcast from Salt Lake City to Californian church members, Elder Clinton Cook instructed, “Give your best to this most significant effort to support in every way possible, the sacred institution of marriage.”

Mormons’ best efforts proved essential. Though California’s 770,000 Latter Day Saints make up 2 two percent of the population, Mormons contributed over half of the $40 million used in the Prop 8 battle. In the last two weeks of the campaign, the Protect Marriage Coalition received a $1 million donation from Alan C. Ashton, grandson of a former president of the LDS church. Not only did Mormons give money, they gave time. One strategist for Protect Marriage, Jeff Flint, estimated that Mormons made up 80 to 90 percent of the early door-to-door volunteers. Freg Karger, a leader of Californians Against Hate and Prop 8 opponent, says, “We were surprised by how heavy they came into this. … Without their millions of dollars and ground troops, it would have been a very different ‘Yes on 8’ campaign.”

Long known as reliable fundraisers and behind-the-scenes organizers in Republican politics, Mormons made Proposition 8 their coming out party as a social conservative force. But their involvement came at a price. Justin Hart, a member of the LDS church and a conservative commentator, laments, “There was this huge target put on our backs.”

In the final days of the campaign, a pro-gay marriage ad, “Home Invasion,” depicted Mormon missionaries ransacking the home of a lesbian couple, taking their wedding rings, and tearing up their marriage license. Tom Hanks called Mormon Prop 8 supporters, “un-American.” One Utah lawyer, Nadine Hansen, set up a website, “Mormonsfor8.com,” which encouraged dissenting Mormons to “out” contributors to “Yes for 8” as Mormons and post information about their wards and places of work.

Because of the backlash, Mormons have shied away from media coverage they cannot control. LDS members who were directly involved with Prop 8 have been asked not to comment to the media. But the institutional church has gone on a press offensive, inviting journalists into its newest temple and discussing their involvement in politics. Shrewdly, Mormon leaders have shifted the debate about marriage to a debate about free exercise of religion. Elder Clinton Cook in an address to LDS members warned that the acceptance of gay marriage would inevitably lead to “legal penalties and social ostracism” for the religious. In this formulation, Mormons are just one of many faith groups seeking to protect their freedom of conscience.

The combination of political strength Mormons demonstrated in the campaign and their perceived suffering afterwards has bonded them to other religious conservatives. “They wanted to show other religions that they saved them,” Hart says. “When we get beat up in the press, it is a badge of honor. And in the conservative movement, it has endeared us to a lot of different groups. They say, ‘Wow, thanks to the Mormons for making it happen.’”

After Prop 8, evangelical opinion leaders exhorted their audiences to stop worrying and learn to love the Latter Day Saints. John Mark Reynolds, a professor at evangelical Biola University wrote, “In the battle for the family…… traditional Christians have no better friends than the Mormon faithful.” A petition to thank the LDS church for its participation in the Prop 8 campaign circulated on conservative websites, and James Dobson signed it. Presbyterian writer John Schroeder said, “We Evangelicals must thank our Mormon cousins. …… They, along with our Catholic brethren, were better organized than us and that provided a base from which we could all work together to get this job done.”

Social conservatives stand to gain much from extending their coalition. As the Prop 8 campaign highlighted, Latter Day Saints offer resources and organization to a movement that often finds itself underfunded and adrift. But the downsides of such an alliance are significant. Though they are fast growing group, Mormons are still a religious minority, concentrated in the mountain West. Their historical and theological baggage may be too much for a mainstream political movement to bear. Evangelicals and Catholics have based their co-operation on a shared belief in the doctrines of the Nicene Creed. Mormons have a continuing revelation, one that many orthodox Christians believe to be flexible in the face of political exigencies. Polygamy was suspended in the LDS church once statehood was offered to Utah, and blacks were allowed to enter the Mormon priesthood not long after protests made Mormon beliefs in the origin of racial differences a national embarrassment. Christians may ask: will the LDS church eventually leave behind its current social commitments?

There are downsides to an alliance for Mormons as well. By hitching themselves to the conservative movement, Mormons risk alienating many co-religionists who have enjoyed a religious community that has for several generations remained politically diverse.

Political realities have made social conservatives open to co-operation with Mormons. Without the LDS church, gay marriage would remain settled law in California. Losing ground among the young and the educated, social conservatives need to be creative in building a constituency for their ideas. But inviting the LDS into the movement will test the limits of co-belligerence. There is something amiss about a mutable and pluralistic coalition claiming to stand against the dictatorship of relativism.