People need to contextualize Santorum's remarks in the context of Big Government Conservatism.
In order to set up the context, you need to do some myth-busting. Myth 1: Conservatives favor small government. Conservatives only oppose Liberal Big Government.
Conservatives favor Big Moral Government and Big Law Enforcement Government and Big Military Government. Conservatives want a government bureaucrat at the foot of every bed, at the opening of every womb, and in the center of every marriage ceremony. Conservatives need Washington to sanctify and protect their moral beliefs. They look to Government contracts and bureaucrats for verification and sanctification of their beliefs. They think that if Washington allows or prevents gay marriage, it means something morally. In their universe Big Government lords over their moral content. In my universe, I don't want a government bureaucrat anywhere near the private morality of free individuals. The state should only intervene when one individual harms another.
Conservatives need Washington to defend their moral beliefs. Most people make their pact with God. Conservatives make their pact with Government, who enforces their pact with God.
As a Liberal, I don't care what Washington says about marriage - and I literally don't care how FREE consenting adults arrange their own sacred moral contracts, provided they don't tell me who to marry or how to interpret my own marriage. As long as they don't interfere with my private life, I could care less what they do. I'm too busy living my life to worry if there are two gay adults living next door. Unlike Conservatives, I don't care what straight or homosexual adults do in the privacy of their own homes - I don't peer out my window, or worried about what others do in the privacy of their own lives. And I don't care what kind of stupid government contract consenting adults get to "sanctify" their love. Why do I not care? Because I don't give the same power to Government contracts that conservatives do. Those contracts don't do not and can not define what is sacred or moral for me.
Conservatives believe deeply in Big Government marriage contracts. They care what Washington says about marriage. They look to Washington for the meaning of marriage. If Washington says marriage is between a man and woman, conservatives are happy. If Washington allows gay marriage, conservatives are outraged. I say, who cares what Washington says. It is not a bureaucrat's job to limit the rights and freedoms of consenting adults provided they don't harm other people. Washington should not decide the sacred content of marriage, rather, they should maximize the freedom and rights and contractual options of the widest number of people, and let adults consenting decide the rest. Washington should have absolutely no say in a free individual's sexuality or religion or gender or race provided that said free individual does not harm anyone else. Washington is not supposed to create or shape the moral environment of the individual. It exists only to defend the homeland and enforce the contracts of free individuals. While I may be personally disgusted by certain physical acts, I don't need nor want Big Government to sanctify or dignify that disgust. I don't need Washington to be my Big Brother - my protector who jealously defends my private sense of moral decency. I don't turn to Washington for my beliefs. Conservatives, on the other hand, require Big Government to protect and enforce their beliefs. They're not happy unless their is a centralized bureaucrat enforcing their private morality on all free individuals.
God help us because these people are one more homeland attack from the kind of rabid Christian moralism that Hitler exploited as Weimar crumbled. A word to the wise: when desperate societies add religion and government imposed morality to the mix, they go in search of evil scapegoats to torture. There is very much a precedent for this - and it always starts with hyper-moral homelanders looking to burn witches or blacks or gays or illegals at the stake. What Conservatives need now is a charismatic leader promising moral renewal. It usually starts with the phrase "Take your country back!" - which is straight out Weimar circa 1930.