The only thing clear right now about the U.S. Supreme Court’s pending decision on the Defense of Marriage Act -- the law that bars the federal government’s recognition of same-sex marriages -- is that Americans will read the verdict as the latest salvo in a long-running culture war. But it is worth remembering that this is a culture war that is increasingly being fought internationally -- and often in terms that do not line up with the debate in the United States. Americans have become accustomed to thinking of the argument against gay marriage as being motivated by religious conservatism. But that is not necessarily true elsewhere.

France offers an instructive example. Although 60 percent of the public supports gay marriage, the country has been beset by vitriolic protests since the National Assembly narrowly passed a marriage equality law last spring. From a distance, the hundreds of thousands of people who took to the streets may have seemed little different from the evangelical activists often seen at similar demonstrations in the United States. But Americans would be surprised to discover how different their motivations often are.

To be sure, religion is not irrelevant to the French protests. The most prominent protest leader, a comedian who adopted the nom de guerre Frigide Barjot, a snarky nod to the 1960s actress and sex symbol Brigitte Bardot, embraced a fervent Catholicism during a pilgrimage to Lourdes. (She now calls herself “Jesus’ press secretary.”) Catholic clergy have denounced the marriage legislation, and several religious associations have helped organize the protests.

But opponents of marriage equality in France’s mainstream parties have mostly kept their distance from religious groups. Relatively few of the street protesters interviewed by reporters talk of God, wave the Bible, or have verses from Leviticus tattooed on their arms. (Which should come as no surprise, given that France is a largely secular place, where barely half the population even still identifies itself as Catholic and regular religious attendance does not even reach ten percent.) Indeed, the most prominent opposition has come from the ranks of professional groups such as law professors and psychoanalysts, whose U.S. counterparts generally favor marriage equality by large margins. A considerable number of public intellectuals have also expressed loud opposition to the law, including the essayist Alain Finkielkraut, the novelist Jean d’Ormesson, and the philosopher Sylviane Agacinski (the wife of former Socialist Prime Minister Lionel Jospin).

Commentators have generally explained the protests by positing, as Jocelyne Cesari did recently in The National Interest, that “French collective values remain unconsciously connected to a traditional vision of society.” But in truth, the extent of opposition to marriage equality has at least as much to do with the vexed and tortuous story of a quintessentially modern phenomenon: French feminism.

Americans often think of France as a country well disposed to feminism, thanks to the pioneering writings of Simone de Beauvoir and others. And the reputation is not without reason. Abortion has been legal in France since 1975, and French women enjoy paid maternity leave and subsidized child care. In June 2000, the French Parliament passed a law without parallel in the United States (although quickly watered it down) mandating that political parties designate women as half of all their candidates for elected office.

Feminist issues have also divided the French intellectual world, however, and the disputes have strongly influenced how the marriage equality issue has played out. An important current of French thought, which has no real American equivalent, has maintained that while women deserve equal rights, these rights must not entail the supposed erasure of sexual difference. Historians and philosophers such as Mona Ozouf and Philippe Raynaud have seen a particular threat in American-style protections against sexual harassment, which they have labeled “sexual Stalinism.” The sociologist Irène Théry has called for a féminisme à la française that acknowledges the “asymmetrical pleasures of seduction.” The philosopher Sylviane Agacinski goes so far as to call sexual difference the true basis for sexual equality in law. The “parity” in elections demanded by the 2000 law, in her view, reflected the natural division of the human race into complementary male and female halves. Other feminists countered that the law should pay no attention to gender beyond guaranteeing equal rights for all (the American historian Joan Scott, herself a frequent target of French criticism, has keenly analyzed all of this).

Though abstruse by U.S. standards, the debates reflect deep anxieties felt by French elites. Not only has France’s geopolitical position slipped and its previous cultural eminence sharply declined -- this May, the National Assembly even approved a measure allowing university courses to be taught (quelle horreur!) in English -- but the ideological causes that once mobilized large portions of the French population have largely evaporated. (French Marxism is not even a shadow of its former self, and little daylight shines between President François Hollande’s Socialists and the neo-Gaullist Union for a Popular Movement, or UMP, party.)

Many influential French figures, including a good number of former Marxists, have taken refuge in a sort of cult of French national identity. One pillar of the cult is the Republic, with a capital R, which they associate with strict civic equality, even stricter secularism in public life, and educational institutions capable of molding a single, cohesive citizenry. But another pillar is the idea of France as the homeland of sophisticated habits, taste, and culture, which in turn depends, as many intellectuals explain, on the romance, beauty, and mystery generated by the play of sexual difference. In 2011, this position initially, and embarrassingly, led a good number of intellectuals to defend Dominique Strauss-Kahn, the International Monetary Fund chief and presidential hopeful, as a gallant “seducer,” rather than a sexual predator, after a New York hotel employee accused him of rape.

This strong emphasis on the complementary roles of men and women has had a remarkable effect on the French marriage debate. Unlike in the United States, most opponents of marriage equality have had relatively little to say about the morality of homosexual sex acts, or about threats to the “institution of marriage” in general. Instead, they speak above all about children, insisting that a psychologically healthy family life rests on the union of a man and woman. Back in 1999, when the French Parliament approved a form of civil union, much of the opposition centered on this issue.

This spring, precisely the same concerns have dominated the manifestos against “marriage for all” issued by groups of law professors and psychologists. And interviews with ordinary protesters have shown just how effectively the arguments of philosophers have filtered down to street level, with one figure after another explaining their opposition to the reform in the same way. To quote a popular protest banner: “Un père et une mère c’est élémentaire” (“A father and a mother is elementary”). And the 60 percent support for same-sex marriage has not changed the fact that a majority still favors banning child adoption by homosexual couples. In short, although religion and homophobia obviously fed into the recent protests, the rhetoric employed by the opposition has trickled down from the intellectuals (as one might, indeed, expect in France).

The question is whether this opposition will continue to influence French politics now that equality is the law of the land and gay marriages have started to take place. My own guess is no. Despite the surprising extent of the protests, support for marriage equality has nonetheless increased steadily over the years, as in most other Western countries, and the pattern is likely to continue. So while the leaders of the UMP, France’s main center-right party, mostly opposed the reform, they are unlikely to risk reversing it if and when they come back into power. Those men and women who oppose marriage equality out of religious conviction or prejudice will gravitate to the extreme right National Front, if they have not already done so. The more mainstream opponents, in contrast, will probably acknowledge that phenomenon for which the French language has the perfect phrase: un fait accompli.