Conservative Christians have lost the fight over gay marriage and, as we have seen, did so decades before anyone even thought same-sex marriage was a possibility. Gay-marriage proponents succeeded so quickly because they showed the public that what they were fighting for was consonant with what most post-1960s Americans already believed about the meaning of sex and marriage. The question Western Christians face now is whether or not they are going to lose Christianity altogether in this new dispensation.

Twenty years ago, new president Bill Clinton stepped on a political landmine when he tried to fulfill a campaign promise to permit gay soldiers to serve openly. Same-sex marriage barely registered as a political cause; the country was then three years away from the Defense of Marriage Act and four years from comedian Ellen DeGeneres’s prime-time coming out.

Then came what historians will one day recall as a cultural revolution. Now we’re entering the endgame of the struggle over gay rights and the meaning of homosexuality. Conservatives have been routed, both in court and increasingly in the court of public opinion. It is commonly believed that the only reason to oppose same-sex marriage is rank bigotry or for religious reasons, neither of which—the argument goes—has any place in determining laws or public standards.

The magnitude of the defeat suffered by moral traditionalists will become ever clearer as older Americans pass from the scene. Poll after poll shows that for the young, homosexuality is normal and gay marriage is no big deal—except, of course, if one opposes it, in which case one has the approximate moral status of a segregationist in the late 1960s.

All this is, in fact, a much bigger deal than most people on both sides realize, and for a reason that eludes even ardent opponents of gay rights. Back in 1993, a cover story in The Nation identified the gay-rights cause as the summit and keystone of the culture war:

All the crosscurrents of present-day liberation struggles are subsumed in the gay struggle. The gay moment is in some ways similar to the moment that other communities have experienced in the nation’s past, but it is also something more, because sexual identity is in crisis throughout the population, and gay people—at once the most conspicuous subjects and objects of the crisis—have been forced to invent a complete cosmology to grasp it. No one says the changes will come easily. But it’s just possible that a small and despised sexual minority will change America forever.

They were right, and though the word “cosmology” may strike readers as philosophically grandiose, its use now appears downright prophetic. The struggle for the rights of “a small and despised sexual minority” would not have succeeded if the old Christian cosmology had held: put bluntly, the gay-rights cause has succeeded precisely because the Christian cosmology has dissipated in the mind of the West.

Same-sex marriage strikes the decisive blow against the old order. The Nation’s triumphalist rhetoric from two decades ago is not overripe; the radicals appreciated what was at stake far better than did many—especially bourgeois apologists for same-sex marriage as a conservative phenomenon. Gay marriage will indeed change America forever, in ways that are only now becoming visible. For better or for worse, it will make ours a far less Christian culture. It already is doing exactly that.

When they were writing the widely acclaimed 2010 book American Grace, a comprehensive study of contemporary religious belief and practice, political scientists Robert D. Putnam and David E. Campbell noticed two inverse trend lines in social-science measures, both starting around 1990.

They found that young Americans coming into adulthood at that time began to accept homosexuality as morally licit in larger numbers. They also observed that younger Americans began more and more to fall away from organized religion. The evangelical boom of the 1970s and 1980s stopped, and if not for a tsunami of Hispanic immigration the U.S. Catholic church would be losing adherents at the same rate as the long-dwindling Protestant mainline.

Over time, the data showed, attitudes on moral issues proved to be strong predictors of religious engagement. In particular, the more liberal one was on homosexuality, the less likely one was to claim religious affiliation. It’s not that younger Americans were becoming atheists. Rather, most of them identify as “spiritual, but not religious.” Combined with atheists and agnostics, these “Nones”—the term is Putnam’s and Campbell’s—comprise the nation’s fastest-growing faith demographic.

Indeed, according to a 2012 Pew Research Center study, the Nones comprise one out of three Americans under 30. This is not simply a matter of young people doing what young people tend to do: keep church at arm’s length until they settle down. Pew’s Greg Smith told NPR that this generation is more religiously unaffiliated than any on record. Putnam—the Harvard scholar best known for his best-selling civic culture study Bowling Alone—has said that there’s no reason to think they will return to church in significant numbers as they age.

Putnam and Campbell were careful to say in American Grace that correlation is not causation, but they did point out that as gay activism moved toward center stage in American political life—around the time of The Nation’s cover story—the vivid public role many Christian leaders took in opposing gay rights alienated young Americans from organized religion.

In a dinner conversation not long after the publication of American Grace, Putnam told me that Christian churches would have to liberalize on sexual teaching if they hoped to retain the loyalty of younger generations. This seems at first like a reasonable conclusion, but the experience of America’s liberal denominations belies that prescription. Mainline Protestant churches, which have been far more accepting of homosexuality and sexual liberation in general, have continued their stark membership decline.

It seems that when people decide that historically normative Christianity is wrong about sex, they typically don’t find a church that endorses their liberal views. They quit going to church altogether.

This raises a critically important question: is sex the linchpin of Christian cultural order? Is it really the case that to cast off Christian teaching on sex and sexuality is to remove the factor that gives—or gave—Christianity its power as a social force?

Read More