By Sara Grossman, Special to CNN

(CNN) - On Sunday, pastor Jim Garlow of Skyline Church in California stood before his congregation of more than 2,000 and told them he would be making an unusual announcement.

The pastor proceeded to warn his audience against voting for a candidate in the upcoming midterm elections who supports gay marriage and abortion, even if that candidate, Carl DeMaio, is a Republican.

Garlow, an outspoken evangelical who played a major role in organizing Christian groups in support of California’s anti-gay marriage Proposition 8, spoke plainly: He would not be supporting the Republican in this race.

“I know enough that you cannot have the advancing of the radical homosexual agenda and religious liberty at the same time, in the same nation,” he preached. “One will win, and one will lose.”

Instead, Garlow told his followers he would be endorsing DeMaio’s rival, Democratic incumbent Scott Peters, representative for California’s 52nd District, to send a scathing message to Republican leadership that candidates who back abortion and gay rights are unacceptable to the party’s Christian base.

Garlow is one of a growing number of Americans who say that religion should play a greater role in politics, according to the findings of a recent study by the Pew Research Forum's Religion & Public Life Project.

The study found that almost three-quarters of the American public — 72% — believes that religion’s influence is waning in public life, the highest level in Pew Research polling over the past 10 years.

And many Americans say that trend is a bad thing, the study found.

“A growing share of the American public wants religion to play a role in U.S. politics,” the Pew study authors write.

What kind of role?

Let’s start with pastors, like Garlow, openly endorsing political candidates.

Nearly a third of Americans say they want houses of worship to back particular candidates, despite IRS rules that prohibit churches from doing so if they want to remain tax exempt. That’s an increase of 8 percentage points since 2010.

An even higher percentage - nearly half of all Americans - said churches and other religious institutions should openly express their views on social and political issues, an increase of 6% since 2010.

The findings of the Pew study contradict what seemed to be a trend toward increased secularization in American social and political life, surprising experts like Seth Dowland, an assistant professor of American religious history at Pacific Lutheran University in Washington state.

Dowland hypothesizes that this increased desire for religion in politics might be due to President Obama’s perceived lack of religion — as compared with former President George W. Bush, at least.

Though Bush made faith a major part of his public identity, Obama has not been quite so outspoken.

Obama "hasn't emphasized his Christianity as much as Bush did, perhaps because Obama's supporters are quite a bit less religious than Bush's were,” Dowland said. “As a result, Americans perceive that we have less religion in public life.”

Dowland added that evangelical Christians have a “nostalgia for an era where the society wasn’t as crass and where Protestant Christians had moral control that evangelicals feel is lost.”

This sentiment may have contributed to the increased support for religious leaders discussing politics from the pulpit.

Garlow also pointed to the current political situation, saying that Obama and other left-leaning leaders have “overplayed their hands” by enacting laws that go against the desires of the people, or at least those of American evangelicals.

The evangelical pastor cited the enactment of gay marriage in many states by court order rather than by a vote by the citizenry.

“We have legal anarchy,” he said. “People get that there’s a legal injustice taking place.”

Garlow said his sermons regularly include a range of political issues, including the national debt, support for Israel and abortion, although he said that more often than not, these politicized issues don’t come up at all.

Over the weekend, he was specifically participating in Pulpit Freedom Sunday, an annual event in which pastors across the nation openly discuss “the intersection of the political realm with the scriptural Truth,” according to the website for Alliance Defending Freedom.

It’s also meant as a test of those IRS rules against politicking in the pulpit, rules that conservatives like Garlow abhor.

According to Alliance Defending Freedom spokesman Nick Bouknight, about 1,800 pastors participated in Pulpit Freedom Sunday this year.

Though Garlow’s congregation might applaud these politically infused sermons, others are dismayed.

“What about the integrity of the political process?” asked Barry Lynn, director of the nonprofit Americans United for Separation of Church and State.

Lynn’s organization has lobbied the IRS to investigate churches that participate in such openly political speech and to revoke their tax-exempt status.

But in recent years, the IRS has been reluctant to take that step.

Even so, Lynn said he is not particularly concerned by the findings of the Pew survey, saying that the language of the questions was somewhat vague and could be interpreted widely.

“It’s not easy to understand what’s in people’s heads when they hear these questions,” he said. “If the question was ‘Should your local church be able to share views on abortion and maintain tax exemption?’ you might get a more nuanced response.”

Lynn also said he was heartened that a great majority of respondents in the Pew poll - 63% - responded negatively when asked whether churches should go so far as to endorse candidates for office.

In any case, megachurches like Skyline Church in California have become rich opportunities for conservative political leaders looking to appeal to a solid bloc of voters.

“We’re seeing a greater consolidation of Christians into fewer and fewer (larger and larger) churches,” said Kate Bowler, a professor of Christian history at Duke University.

“Megachurch leaders are becoming natural allies and representatives for politicians looking for large, engaged audiences of evangelicals.”

Garlow says he is preaching the Bible, not politics.

“I haven’t been outspoken on political issues. I've been outspoken on biblical, moral and theological issues,” he said. “My opinions don’t matter. God’s do.”