To follow-up on Jamelle's analysis of Rick Santorum's repudiation of fundamental First Amendment values, it's worth considering some comments made by Santorum in 2008, when he wasn't running for president and could be even more candid:
But is there such thing as a sincere liberal Christian, which says that we basically take this document and re-write it ourselves? Is that really Christian? That’s a bigger question for me. And the answer is, no, it’s not. I don’t think there is such a thing. To take what is plainly written and say that I don’t agree with that, therefore, I don’t have to pay attention to it, means you’re not what you say you are. You’re a liberal something, but you’re not a Christian. That’s sort of how I look at it.
When you go so far afield of that and take what is a salvation story and turn it into a liberation theology story, which is done in the Catholic world as well as in the evangelical world, you have abandoned Christendom, in my opinion. And you don’t have a right to claim it.
Santorum, in other words, is arguing that people who don't share his political views aren't really Christian. It's an appalling view, but it's a common Republican double standard. Bill Clinton and Barack Obama, who regularly attend church, have their faith questioned repeatedly; while Ronald Reagan and George W. Bush, who rarely attended church, were not subject to any such doubts.
Perhaps the ultimate example of this was inadvertently demonstrated in a fawning New York Times Magazine profile of the Princeton "natural law" theorist Robert George. You will not be surprised to learn that for George, as for Santorum, "natural law" has political implications that always happen to map exactly on to reactionary Republican political consequences. Catholic teachings that might prove inconvenient to Republican policy preferences or require sacrifices of important Republican constituencies—on subjects such as poverty or the death penalty—can be safely ignored, but if you don't favor embedding the church's teachings on human sexuality into secular law this is unacceptable. It's dismaying indeed that a recycler of these silly hypocrisies is leading national polls for the Republican presidential nomination.