It's not every Sunday that the image of a major presidential candidate dwarfs the pulpit of a simple country church in southern Minnesota, but this was no ordinary sermon at Grace Christian Church in Albert Lea.

With 37 days to go before the election, the Rev. George Marin was taking part in a special calling, one shared by dozens of pastors across the nation, to preach what he sees as a biblical basis for voting.

So last Sunday, during a service that featured 50 rapturous congregants speaking in tongues, a YouTube video of Barack Obama appeared on a large overhead projection screen. In the video Obama told the Rev. Rick Warren in California that the question of when life begins is "above my pay grade."

"This does not fly," Marin bellowed into a wireless microphone. Castigating the Democratic candidate's abortion-rights stand, Marin exhorted his followers amid shouts and applause: "I am calling on you to reject this man as the next president of the United States."

Sermons like Marin's are a sign of growing fervor among Christian conservatives who see this year's presidential election as a watershed moment for their participation in political life.

Energized by Sarah Palin's selection as John McCain's running mate on the Republican ticket, voters across the nation who oppose abortion are rallying their forces in ways that sometimes challenge conventional strictures on the role of pastors and religion in public life.

In Minnesota, groups such as the Minnesota Family Council are trying to reach 400,000 to 500,000 voters -- potentially a sixth of the state's electorate -- with overtly Christian appeals that define support for "pro-family" candidates as a moral obligation.

"The bottom line is, we want people of faith to get out and vote their biblical values," says Chuck Darrell, the group's spokesman. "If they get out and vote, it's going to have an effect."

Back in the fold

In a small block building across from a shopping center in Eagan, KKMS-AM Christian talk radio hosts Jeff Shell and Lee Michaels are taking calls about the election. It's Thursday afternoon, a few hours before the vice presidential debate, and much of the conversation is about the reverse bigotry that many Christian conservatives feel when they venture out into the public square.

It's part religious battle cry, but also part of the political right's narrative of perceived media persecution of Palin, a kind of latter-day Joan of Arc who brought many alienated evangelicals back into the Republican fold.

"No question about it," says Shell, an elder at the Wooddale Church in Eden Prairie, an evangelical church that counts Gov. Tim Pawlenty as a member. "She reinvigorated McCain's campaign, because a lot of people were lukewarm about him."

Shell and Michaels' show reaches as many as 50,000 listeners in the Twin Cities. But much of the evangelical ground-game involves traditional efforts to get out the vote: distributing voter guides, literature on the issues and voter registration cards.

As part of the Family Council's Mobilize 2008! campaign, some churches have called from the pulpit for people to vote. Among them is Pastor Jim Anderson of the Harbor Church in Hastings. "We're telling people to vote whichever candidate, but vote their values," he said.

'All areas of life'

Few evangelical pastors in Minnesota have crossed the same legal threshold as Marin at Grace Christian -- or the Rev. Gus Booth of the Warroad Community Church, who explicitly endorsed McCain from the pulpit last week, in defiance of Internal Revenue Service rules banning political preaching.

For many affluent suburban megachurches, no matter how conservative, the potential jeopardy to their nonprofit tax status is simply too great to risk. But a national campaign by the Alliance Defense Fund, dubbed "Pulpit Freedom Sunday," reflects a push to put faith into political action.

For Pastor Booth in tiny Warroad on the Canadian border, that means putting a lot of miles on his car, talking to as many as 60 pastors over the past few months.

"Scripture declares us to take the Gospel into all areas of life," he said on a recent morning drive across northern Minnesota. He was delivering pastor's guides for the Family Council's voter campaign, which is targeting 1,300 churches. "The Gospel is supposed to rally people unto itself."

Booth, who may have been the first pastor in the nation to endorse McCain during a sermon in May, is garnering headlines and appearing on TV.

But some Minnesota evangelicals are resisting the upswell of political activism, hewing to the more traditional idea that it cheapens religion.

"If they want to express their values, that's fine," said the Rev. Gregory Boyd of Woodland Hills Church in Maplewood. "I just wish they wouldn't call it Christian, like there's one Christian way to vote."

Others insist GOP candidates in general -- and abortion opponents in particular -- simply make for a better fit for "values" voters.

"McCain is going to be a lot closer, on the whole, to the value system I'm talking about," says David Watkins, pastor at the Heritage Baptist Church in Blaine and a leader in the Christian home-schooling movement.

'It was like, wow'

There is little doubt that in picking Palin, McCain tapped into a mother lode of voters that might not otherwise be there for him.

National polls conducted before Palin joined the ticket suggest that McCain attracted a little more than half of evangelical voters, far below the appeal of President Bush, who got about 70 percent of evangelical voters in 2000 and 80 percent in 2004 and whose efforts to turn out the evangelical vote has been cited as a factor in his reelection.

Christian conservatives have long maintained a mutual distrust of McCain, who has dubbed some of their leaders as intolerant in the past. That left McCain in an uneasy stalemate with Christian conservatives -- perhaps the GOP's single-biggest voting bloc -- until Palin came along, an abortion opponent with evangelical roots, a special-needs infant and a pregnant teenage daughter who's keeping the baby.

"It was like, wow," said Brian Gibson, of Pro-Life Action Ministries in the Twin Cities. "All of a sudden, it's time to do something, and that's when the energy jumped very strongly. And it's been there ever since."

While Palin has added energy, evangelicals say their voters aren't marching in lockstep. Some polls suggest many new evangelicals, particularly young evangelicals, trend increasingly independent and express concern not only about abortion but also about poverty and the environment.

Despite their numbers -- about a third of Minnesota's likely voters describe themselves as evangelical Christians -- it's also uncertain whether they will ultimately add to McCain's tally.

"It's a set of voters who have become so reliably Republican that it's hard to see a boost beyond what they've contributed before," said Gustavus Adolphus College political scientist Chris Gilbert.

So for activists who want to emphasize abortion and same-sex marriage, that brings the equation back to turning out the base on their issues.

"Pastors are starting to recognize that they have to do something," said abortion foe Gary Borgendale, a local ministry director at KKMS who attended Marin's "Pulpit Freedom" sermon in Albert Lea. "They recognize that there are differences between the candidates."

Kevin Diaz • 202-408-2753