After the White House decreed this month that religious employers would have to pay for workers' birth control, it was no surprise that Roman Catholic leaders would protest. That evangelical Protestants would rally to their cause was less expected and unthinkable even a generation ago.
"It's just the common good. We're all brothers. They're Christians, we're Christians," said Thomas Fallon, 43, a general contractor who lives in Auburn, Mass., and converted to Southern Baptism from Catholicism. "We have that belief system that this is wrong that the government is trying to impose on our religious beliefs."
The support reflects how the country's two largest religious affiliations have learned to find common ground in the political arena in the half-century since John F. Kennedy became the nation's only Catholic president. He had to promise a group of Protestant pastors that he wouldn't try to ban divorce or birth control to allay fears of a White House guided on moral issues by the Vatican.
Contraception is one of the very issues that have been a wedge between Catholics and evangelical Protestants for decades. But for Protestants who've rallied to the Catholic bishops' side, the question this time is one of religious liberty rather than dogma.
Even after the Obama administration hastily revised the order to require insurance companies, rather than religious employers, to pay for birth control, many evangelicals say the bishops are right to reject the new rule as the same violation of conscience in a different form.
"I don't think it should be mandated for anybody to have to offer or pay for it," said David Teague, 48, a salesman who attends The Donelson Fellowship, a Freewill Baptist church in Nashville, Tenn. "The government is, in my view, way too intrusive in many areas, this being one of them."
Not long ago, even the claim that Catholics and Protestants are both Christians would have raised objections in some quarters, let alone the idea that they stand together on an issue of theological disagreement.
Most of the discontent has been voiced so far by leaders in the evangelical world, like Richard Land, president of the Southern Baptist Convention's Ethics and Religious Liberty Commission, and Albert Mohler, president of the Southern Baptist Theological Seminary.
"You at least have to admire the courage of the Roman Catholic bishops in saying they are willing to go to jail rather than to comply with this," Mohler said in one of his daily podcasts. "How many evangelical presidents and pastors and leaders will be willing to do the same?"
It's also coming from the pews, though, where some Protestant see troubling implications for all religious groups.
"I believe that religiously-affiliated organization, whether they're Catholic, Muslim, Hindu, Protestant, all deserve to function according to their principles and still be funded by the state, and not have to compromise those because of competing system of morality, or secularism," said Emily Boop, 21, a student at Gordon College, a Christian school in Wenham, Mass.
Boop, who describes herself as a theologically conservative Protestant who attends an Anglican church, disagrees with the Catholic Church's ban on contraception. But she supports its right to set its own priorities.
"It's a component that's really central to the Catholic faith, like the sanctity of human life," she said. "It actually undergirds a lot of their civil rights and human dignity doctrine."
Depending on the denomination, Protestants are not completely at ease with contraception, depending on what type is being used and whether it's being used by unmarried couples.
The so-called "morning after" pill, for example, is incompatible with an outlook that opposes methods that prevent the implantation of a fertilized egg, said Denny Standifer, an orthodontist who attends Red Bank Baptist Church in Chattanooga, Tenn.
"We believe life begins at conception and that would be stopping life," he said.
The support from evangelical precincts has been welcome for Catholics.
"The Protestant churches realize what this means," said Mario Guerra, a city councilman in Downey, Calif., and a permanent Catholic deacon. "I really think this is a religious liberty issue that resonates among all religions in our country."
It's a marked change from much of U.S. history, when Protestants and Catholics regarded each other with wariness at best and hostility at worst. Birth control, along with divorce and government funding for parochial schools, were two of the issues cited by advocacy groups like Protestants United for the Separation of Church and State in criticism of the Catholic Church. In 1960, a group calling itself Citizens for Religious Freedom that included the world-famous pastor Norman Vincent Peale formed specifically to try defeating Kennedy's White House bid.
Even today, suspicion remains in some quarters. Four years ago, Sen. John McCain rejected the presidential endorsement of Texas megachurch pastor John Hagee, who had called the Catholic Church "the great whore" and suggested it shaped Adolf Hitler's anti-Semitism. Hagee later said his comments were taken out of context.
"It's changed especially in the last 15 years, where Catholics and Evangelicals have found themselves at pro-life marches and fighting similar battles on marriage," said Michael Cromartie, director of the Evangelical Studies Project at the Ethics and Public Policy Center in Washington, D.C. "When you find yourself on the same side on moral issues, the theological differences are bracketed to the side."
But there may be another explanation: presidential politics. Evangelicals, like those who have criticized Obama over the rule, generally take a dim view of his administration and voted against him in 2008, said Randall Balmer, a professor of religious history at Columbia University.
"They're willing to say, listen, this isn't our issue, but we can score some political points," he said. "The larger picture is the desperation of the religious right to remain politically relevant."
Associated Press writers Jay Lindsay in Boston and Travis Loller in Nashville, Tenn., contributed to this report.