Republican presidential candidate Texas Gov. Rick Perry speaks at the Iowa Faith & Freedom Coalition presidential candidate forum, in Des Moines, Iowa. (Nati Harnik/AP)

— Six of the eight Republican presidential candidates vying for the hearts of social conservatives filed on and off stage in a cavernous hall here Saturday evening to each proclaim allegiance to conservative evangelical principles.

In speeches woven with spiritual references, the candidates spoke of reversing abortion rights and defending traditional marriage, and they cast the 2012 election as one that would determine whether the nation’s very freedom endures.

“Stupid people are ruining America,” businessman Herman Cain thundered in a well-received address before about 1,000 activists at the Iowa Faith & Freedom Coalition’s annual dinner.

“The Founding Fathers got it right. We have to be the Defending Fathers,” Cain said. “We’ve got to get it right in 2012, and I believe that we will, because we’re reminded that while we are on this journey, we all have just a limited amount of time to be here, and we have to decide how we’re going to use our time, our talents and our treasure in order to make a difference.”

Cain’s rise in the polls — and his comments to CNN that put his position against abortion in doubt — made him a target on the stage. Texas Gov. Rick Perry took a swipe at him, although he did not refer directly to the interview, in which Cain said that families should be able to abort a pregnancy in instances of incest and rape.

“It is a liberal canard to say, ‘I am personally pro-life, but government should stay out of that decision,’ ” Perry said. “That is not pro-life. That is pro-having-your-cake-and-eating-it-too.”

In his remarks here, Cain reaffirmed his opposition to abortion, saying he thought the procedure should be declared “illegal across this country” and pledging not to sign any legislation granting government funds for abortions.

The candidates forum came as competition for religious conservatives here is intensifying among the White House hopefuls, with the Jan. 3 Iowa caucuses approaching. Each candidate gave a 10-minute speech and took a few questions from the event sponsors. They used their turns to try to cement their conservative credentials and show that they would be the movement’s best standard-bearer in the race against President Obama.

The activists, who gathered in a showroom hall here at the Iowa State Fairgrounds over fried chicken and fruit punch, seemed emboldened and energized. And while candidate considered the front-runner was absent from the stage — former Massachusetts governor Mitt Romney — those who did speak here made oblique references to him.

“Being pro-life is not a matter of campaign convenience. It is a core conviction,” Perry said, drawing a contrast not only with Cain but also with Romney, who says he opposes abortion rights but who had supported them earlier in his political career.

“When it comes to faith, it is the core of who I am. It is an essential act as much as breathing is an essential act,” Perry said. “I found the true source of hope and change, and that is a loving God who changes hearts of stone into hearts of flesh.”

Although Romney campaigned in Iowa on Thursday, he did not stay to address the assembled social conservatives. Instead, he was in New Hampshire on Saturday, thanking volunteers at his Manchester campaign office and calling targeted voters.

Although many here do not trust his conservative convictions, Romney maintains a sizeable grass-roots network in Iowa from his 2008 race, made up of more mainstream GOP activists and business types.

Meanwhile, other candidates used the Iowa forum to try to jump-start their struggling campaigns. Former House speaker Newt Gingrich (Ga.) was one of them, and he received some of the heartiest applause of the night.

“We can have a dramatically better Christmas in 2012 if it is the ‘Goodbye, Obama, Christmas,’ ” Gingrich said, drawing laughter. “One of our slogans should be: ‘You want a great Christmas? Vote against Obama.’ Even for many Democrats, that will begin to be an appealing idea.”

Rep. Michele Bachmann (Minn.) also took aim at the president. “People have made up their mind,” she said. “They have decided that Barack Obama won’t have a second term. Now the question will be who will we replace Barack Obama with? Will it be a candidate who has a proven record of standing for us and for what we believe in? This is the year when social conservatives can have it all.”

Bachmann ticked through her efforts in Congress, saying she wrote the unsuccessful bills to repeal Obama’s health-care law and to repeal the Dodd-Frank financial regulatory overhaul. She pledged to shut down the federal departments of Education, Energy, Interior and Commerce, as well as the Environmental Protection Agency. “I’ll shut it down,” Bachmann said, describing herself as “a fighter.”

She added: “I’ve raised 28 children. I’m the old woman in the shoe. I am tough love.”

Rep. Ron Paul (Tex.) and former senator Rick Santorum (Pa.) also addressed the forum.