My friend Tim Dalrymple asks just this question over at Patheos. He shared his observation with Fred Barnes, who put it this way:  

Foes of gay rights are now seen by the press as fighting the bad war, roughly analogous to Vietnam. Pro-lifers are waging the good war, like World War II. “You get much less grief fighting against abortion than you do fighting to preserve traditional marriage,” says Marjorie Dannenfelser, president of the Susan B. Anthony List.

I’ve seen this reality on college campuses. Speak to conservative college students and you’ll generally find enthusiastic pro-life support and deep ambivalence about — if not outright hostility to — preserving traditional marriage. Younger conservatives want to talk about life. They don’t want to talk about sexuality. In the larger culture, support for life is growing, with the percentage of Americans identifying as pro-life now in rough parity (and sometimes exceeding) the percentage of Americans calling themselves pro-choice. And while there’s no question that the media has long exaggerated public support for same-sex marriage (marriage amendments keep winning in state after state), there’s also no question that general polling trends are decidedly negative.

In explaining this phenomenon, Tim sees a number of factors at work. First, the life argument is simply easier to make. You don’t have to appeal to scripture or other holy texts to argue that a child should not be dismembered in his or her mother’s womb. By contrast, marriage arguments tend to be more abstract, especially since there’s no readily identifiable “victim” of gay marriage. Second, the media and liberal establishment relentlessly stigmatize supporters of traditional marriage, often labeling its advocates as no better than the white supremacists of the bygone South. This campaign has had a profound effect. As Tim notes:

Consider this little bit of anecdotal information. As an editor and director for a large religion website now, I can tell you: It’s substantially easier to find Christians and evangelicals to write on the abortion issue than it is to find ones who will write on same-sex marriage. Academics in particular are terrified that anything critical of homosexuality or same-sex marriage will come up before hiring or tenure committees. One of the first subjects we addressed in our “Public Square” at Patheos was the same-sex marriage debate, and nearly every person I approached to write on the topic had to ask himself or herself: “Am I willing to give up the next job, the next promotion, the next award, because of my views on this topic?”

I agree with Tim’s explanations, but I’d like to add another. After more than a generation of no-fault divorce, the very concept of “traditional marriage” is seeping out of our cultural DNA, replaced, sadly, by the core conviction that marriage is no longer a covenant, but a contract — specifically a contract for the fulfillment and enjoyment of adults. Our churches not only acquiesced in this cultural change, many of them continue to facilitate it even as they argue against same-sex marriage. There are many taboos in the modern evangelical church, and one of them is “judging” anyone’s divorce. Even wayward and unfaithful spouses will rationalize their betrayals through long lists of real and imagined slights, and church discipline for adultery and divorce is largely a thing of the past.  

What kind of message does this send? Imagine the incredulity of a Christian college student — themselves too often the product of a broken home, where they had a front-row seat to their parents’ contentious festival of self-love — watching a thrice-married fellow congregant rail against gay marriage. It just doesn’t add up.

The battle over marriage, frankly, needs to broaden. We shouldn’t necessarily speak of “defending traditional marriage” when traditional marriage has already been mortally wounded by no-fault divorce. Perhaps we should instead emphasize marriage restoration over marriage defense. What do social conservatives want? To restore marriage to its rightful place and definition in our culture (which includes defining it as a covenant, not a contract) and to repair what is broken. To be sure, making and winning such an argument is an immense cultural challenge, but as the pro-life movement has demonstrated, courage, persistence, and truth can turn the tide.