I came away from a debate on gay marriage between Douglas Wilson and Andrew Sullivan deeply impressed with the difficulties that Christians have, and will continue to have, defending a biblical view of marriage to the American public. It will take nothing short of a cultural revolution for biblical arguments to be heard, much less to become persuasive.

Sullivan clearly has all the hurrah words on his side - love, happiness, equality. How can anyone stand in the way of true love that seeks lifelong commitment in marriage? Sullivan also has liberal order on his side. When Wilson answered a question by citing the Bible, Sullivan pounced. Wilson’s was a fundamentalist, theocratic argument. Sullivan defined democracy as a system that excludes appeals to religious authority from the foundations of public life. He was quick to add that he is a resolute foe of political correctness, but one wouldn’t have known it from his mercurial move from Wilson’s citation of the Bible to theocracy to the Taliban to warnings about violent suppression of dissent. Sullivan demanded that Wilson defend his position with secular, civil arguments, not theocratic ones, and in this demand Sullivan has the support of liberal polity.

Sullivan’s is a rigid standard for public discourse that leaves biblically-grounded Christians with little to say. The claim that legalizing gay marriage will make the legalization of polygamy easier, as Wilson repeatedly argued, is coherent, but doesn’t have much purchase. Nobody seems to be much worried about a polygamous future for America, and making polygamy the centerpiece of opposition to gay marriage looks too much like fear-mongering.

That leaves Christians with the option of making theologically rich, biblically founded arguments against gay marriage. But do we have the vocabulary ready to hand? And even if we do, does the vocabulary we have make any sense to the public at large?

Wilson closed the debate with a lovely sketch of the marital shape of redemptive history, from the garden to the rescue of the Bride by the divine Husband to the revelation of a bride from heaven. In order for that to carry any weight, though, people have to be convinced that social institutions should participate in and reflect some sort of cosmic order. Who believes that these days? Wilson tells a cute story, many will say, but what does it have to do with public policy?

If that’s a hard case to make, it’s even harder to make the case that homosexuals are in any way a threat to our civilization. Paul says that homosexual desire is unnatural and, more than that, that the approval of homosexuality is a symptom of advanced cultural decay. Sullivan had no time for this kind of argument: Show me data, he kept saying; show me the specific ways that gay marriage has harmed society or heterosexual marriage in particular. Given his assumptions about what might count as evidence, it’s a hard case to make. To believe Paul, we have to believe that God has standards of sexual behavior, that those standards can be known, and that He judges humans for their conformity to the standards. Who believes that these days?

Sullivan set the contours of the debate early, describing gay marriage as the fulfillment of love. Who can argue with love? But that assumes that children are excluded from the definition of marriage. Sullivan implied that the only alternative would be a medieval arrangement in which marriage exists only for the sake of procreation, but that’s clearly not the case. It’s possible to formulate an intergenerational definition of marriage as the social norm without implying that every sexual act must aim at reproduction. Wilson admitted that heterosexuals, not homosexuals, have done nearly all the damage to marriage, and part of the damage we’ve done is to allow marriage to be defined in the exclusively romantic terms that Sullivan coopts for his own purposes.

In the end, these dilemmas may not matter. Perhaps Christians are called to do no more than speak the truth without worrying about persuasiveness. Perhaps we have entered a phase in which God has closed ears, so that whatever we say sounds like so much gibberish. We can depend on the Spirit to give ears as He pleases.

Whatever the political needs of the moment, the longer-term response to gay marriage requires a renaissance of Christian imagination. Because the only arguments we have are theological ones, and only people whose imaginations are formed by Scripture will find them cogent.