ROBERT SIEGEL, HOST:
As Senator Rick Santorum looks ahead to Super Tuesday, he's likely to keep to a familiar theme: religion in public life. Increasingly, Santorum has criticized John F. Kennedy for advocating the separation of church and state.
NPR's Barbara Bradley Hagerty looks at how the political climate has changed since 1960, when Kennedy delivered his famous speech on the subject.
BARBARA BRADLEY HAGERTY, BYLINE: When Rick Santorum was growing up, he says John F. Kennedy was a hero in his Catholic home. In a speech last year, he said he always heard glowing reports of Kennedy's speech about religion to Protestant ministers in 1960.
RICK SANTORUM: And then, very late in my political career, I had the opportunity to read the speech, and I almost threw up. You should read the speech. It's - in my opinion, it was the beginning of the secular group and the politicians to separate their faith from the public square.
HAGERTY: Yesterday, Santorum said he regrets his graphic language, but he insists that Kennedy's view was wrong.
(SOUNDBITE OF ARCHIVED BROADCAST)
PRESIDENT JOHN F. KENNEDY: I believe in an America where the separation of church and state is absolute, where no Catholic prelate would tell the president, should he be Catholic, how to act. And no Protestant minister would tell his parishioners for whom to vote.
HAGERTY: On Sunday, Santorum told ABC's George Stephanopoulos that Kennedy set the foundation for expelling faith from politics.
(SOUNDBITE OF ABC BROADCAST)
SANTORUM: What kind of country do we live in that says only people of non-faith can come in the public square and make their case?
SHAUN CASEY: I think that's a radical misunderstanding of what Kennedy was trying to convey in that speech.
HAGERTY: Shaun Casey is author of "The Making of a Catholic President," a book about Kennedy. He says Kennedy would have been booed off the stage if he implied there's no place for religion in public life. Casey says Kennedy was explicit: While religious leaders should not tell politicians how to vote, they can - and should - instruct them on faith and morals.
The speech has to be read in context, Casey says. Kennedy was running in a political climate that was openly hostile to Catholics.
CASEY: And the primary issue is the accusation that Catholicism represents a church and a state; that inevitably, to be Catholic means you want to have a Catholic-dominated state, and that Catholic leaders will coerce Catholic politicians to make that so.
HAGERTY: Fifty years later, the political climate is vastly different.
JOHN GREEN: In 1960, the issue was differences between religious affiliations, such as between Protestants and Catholics.
HAGERTY: Back then, says John Green, a political scientist at the University of Akron, many Protestants considered the pope to be a threat. Now, conservative Catholics and Protestants have joined forces, and they consider the big threat to be secularism.
GREEN: Conflict seems to be based around the level of religiosity, with more traditionally religious people in most - if not all - religious communities having different views about politics than those who are more progressive or more liberal, or less traditional.
HAGERTY: Green says Santorum is finding a receptive audience among conservative evangelical Protestants. He won 51 percent of them in Michigan, and is favored among them in polls nationwide.
Santorum says the Obama administration is waging a war on religion, even claiming that the president practices a, quote, phony theology. Shaun Casey says the president is not the only target.
CASEY: One of the reasons I think Santorum is talking about religion is also to shine a bright light on his opponent Mitt Romney's reticence to talk about religion. So it's not just about getting the record straight on JFK, and attacking Democrats. It has the added benefit of shining a bright light on the fact that Mitt Romney is very hesitant to address the issue.
HAGERTY: Mitt Romney is a Mormon, and polls show that makes many Republican primary voters uncomfortable. Romney tried to address that issue five years ago, in a speech modeled on Kennedy's. But unlike 50 years ago, Romney's speech does not appear to have put voters' concerns to rest.
Barbara Bradley Hagerty, NPR News.