In the contemporary debate on the future of marriage, there appears to be, amid many uncertainties, one sure thing. Those who publicly defend traditional marriage can count on being denounced as haters, bigots, or irrational theocrats”and perhaps all of these at once. So I learned after publishing an article in the Washington Post last December titled “On Gay Marriage, Stop Playing the Hate Card.” I was not making a full-fledged argument against same-sex marriage”only urging Post readers to reject the use of reckless charges of “hate” to shut down debate, and asking them to respect the defenders of marriage as people in possession of an argument . Sadly, many readers leapt to the challenge of confirming my thesis, writing e-mails or commenting online that I must indeed be a hating, bigoted, irrational theocrat.

Lying behind this poisoning of our public discourse is some notably flawed reasoning that it is worth our while to consider in some detail.

In briefly rehearsing well-known defenses of conjugal marriage that others have elaborated elsewhere, I noted in the Post that marriage “has always existed in order to bring men and women together so that children will have mothers and fathers” and that same-sex unions are “not an expansion but a dismantling of the institution.” The response of some readers was not merely that I had not fully fleshed out this argument (which I could readily admit) but that such statements did not even bear the marks of rationality”that they were so obviously wrong that only those in the grip of unreasoning hatred or bigotry could put them forward.

Some of our high public officials, unfortunately, have encouraged this kind of flattening and coarsening of our public discussion. Judge Joseph Tauro, of the federal district court in Boston, in ruling against the constitutionality of section 3 of the Defense of Marriage Act (which defines marriage as between one man and one woman for the purposes of federal law), said last July that the difference between same-sex couples and opposite-sex couples is a “distinction without meaning.” How he claimed to know this, since he did not explain it, is anyone’s guess, but it was enough for him to conclude that Congress, in passing DOMA, had acted on an “animus” that “targets” people on the basis of a “sexual orientation” of which Congress “disapproves.” But DOMA was passed by overwhelming majorities in both houses of Congress, and signed by a Democratic president, for the express purpose of defending the right of the people in each state to govern themselves on the question of marriage. It would never even have been proposed in Congress but for the existence of a movement determined to make an end-run around the institutions of democratic decision-making”determined, that is, to persuade judges like Joseph Tauro to bend the Constitution to suit the purposes of a political agenda. DOMA is just what its title says it is”a defense of marriage against assault by a court-centered strategy. Given the feebleness of his arguments, it’s a fair question just what “animus” the judge himself has toward people who disagree with him.

In late February, Judge Tauro’s view was essentially adopted by the Obama administration, which announced that the Justice Department would no longer defend the constitutionality of section 3 of DOMA but would instead take the opposite position in federal courts. It is perfectly legitimate for presidents to assert their independent judgment about the constitutionality of the laws that govern us. But what passed for judgment in the administration’s analysis was shockingly thin. The most substantial point made in Attorney General Eric Holder’s letter to House Speaker John Boehner was that, during the 1996 debate on DOMA, some members of Congress had expressed “moral disapproval of gays and lesbians and their intimate and family relationships”precisely the kind of stereotype-based thinking and animus the Equal Protection Clause is designed to guard against.”

The disapproval of “moral disapproval”: This moves us closer to the heart of the matter. Not long after Judge Tauro’s decision last summer came the ruling of Judge Vaughn Walker, of the federal district court in San Francisco, striking down California’s Proposition 8, itself a defensive measure passed by a majority of the state’s voters in 2008 after the state’s supreme court invented a right of same-sex marriage under the California constitution. Judge Walker declared that there was no “rational basis” for Prop. 8. “Tradition alone,” he wrote, “cannot form a rational basis for a law.” Tradition normally has a presumption in its favor in such inquiries, but not for Judge Walker. He sniffed out what was really going on, declaring that “moral and religious views form the only basis for a belief that same-sex couples are different from opposite-sex couples.” The law unavoidably speaks in the name of a community’s moral vision, so to what did the judge really object? He called opposition to same-sex marriage a “private moral choice,” with “private” meaning it was not entitled to enactment as public morality. Clearly, for Judge Walker, the reason for this conclusion lay in the second term of the phrase of his, “moral and religious views.” In the most telling passage of his opinion, he claimed”as a “finding of fact,” no less”that “religious beliefs that gay and lesbian relationships are sinful . . . harm gays and lesbians.”

There we have it. Marriage only between a man and a woman is a mere “tradition” with no claim on our attention when a claim of “discrimination” is made on the other side. All that this tradition has going for it is the “moral and religious views” of its supporters. But the law embodies moral choices, so why is this moral viewpoint illegitimate as the basis of a law? The problem is that it is driven too much by the religious commitments of those who hold it”and so it must be dismissed from public life and relegated to the realm of “private moral choice,” disallowed from enactment as the view of the majority in a democratic society. So toxic is it to hold certain religious views that merely believing them works a “harm” to other people. Those who hold these views must not only be prevented from enacting those views as the will of the democratic majority; they must, to the extent possible, be silenced in the public square. They must . . . shut up .

Judge Walker’s effort to divorce the moral aims of public policy from traditional, religiously supported moral principles points to the other, even more serious assault made by gay-marriage advocates on the integrity of argument”namely, the charge that the defenders of conjugal marriage want to “impose their religion” on others. This is a serious accusation in a society that prizes freedom of religion. But of course it is not the case that some Americans want to force their unwilling fellow citizens to subscribe to the theological or doctrinal tenets of a particular church. The real point of the accusation, as I argued in the Post , is to “drive the wedge between faith and reason, chasing traditional religious arguments on marriage and morality underground, as private forms of irrationality.”

But why do some participants in our public debates”not just gay-marriage advocates but “secularists” of all stripes (and not a few religious people)”believe that religiously grounded arguments must be “privatized”? Why do they believe that faith and reason must be separated by an unbreachable wall? And why are some arguments that are presented entirely in terms of rational precepts of morality, without reference to theological presuppositions or claims about God’s commandments, treated as suspect”as “theocratic,” no less”if they draw the same moral conclusions as particular religious teachings on the same subject?

A partial explanation, offered by the theologian Alister McGrath, is the assumption that religious faith is “invariably blind faith””unsupported by the evidence of facts available to us, and even contradicted by them. But as McGrath notes, “The simple reality of life is that all of us, irrespective of our views about God, base our lives on beliefs”on things that we cannot prove to be true, but believe to be trustworthy and reliable.” Understood in this way, “faith” is indispensable to all of us, whether we are recognizably “religious” or not. Belief is “not blind,” says McGrath, “it just tries to make the best sense of things on the basis of the limited evidence available.” It is perhaps a touchingly blind faith in the sufficiency of narrow scientific reasoning that fails to recognize this obvious fact of the human condition.

A fuller explanation lies in an erroneous chain of reasoning that runs roughly as follows. Freedom of religion is a special case of freedom of thought. Freedom of thought, for the religious and for “freethinkers” alike, is not safe from theocratic oppression unless steps are taken to separate church and state. But the separation of church and state is perennially under threat unless we take the further step of separating religion and politics, for there is a constant danger that religious believers, thinking and acting according to the teachings of their faith, will seek to establish those teachings as authoritative over whole societies, forcing nonbelievers and members of other sects to obey religious tenets whose moral force they do not recognize. This separation of religion and politics, in turn, is unsustainable so long as contending religious sects are permitted to bring their faith commitments into the public square and to employ the discourse of their doctrines in framing arguments about public policy. Religiously grounded discourse, therefore, must be privatized, sequestered in the precincts of home, family, and church, where it cannot wreak its damage in the public square.

Thus does a course of reasoning issuing from a concern for the threat posed to religious freedom by theocratic tyranny eventuate in the suppression of religious freedom by secular tyranny. Dissenters are not burned at the stake in this benign despotism, but they are effectively silenced by public authority, as when the judges in these recent cases inform a majority of citizens who had voted to preserve the institution of conjugal marriage that their moral judgment is “irrational,” and therefore unconstitutional, precisely to the extent that it finds support in their religious beliefs.

The dubious reasoning of this “secularist syllogism” rests on a fallacy of equivocation, in which “religion and politics” is wrongly made identical with “church and state.” Church and state are authoritative institutions, while religion and politics are activities pursued by individuals, groups, and organic communities. To disestablish a politically authoritative church is to strike a blow for the freedom of all religious believers to act on their beliefs, politically as well as privately. But insisting on the separation of religious discourse from political discourse, isolating the former from the latter by “privatizing” it, moves in exactly the opposite direction, and creates the contradiction found at the center of many modern tyrannies: affirming a mythical freedom by denying the real thing.

McGrath’s insight is relevant here as well. The secularist syllogism supposes that religious belief is necessarily blind, pulling believers away from rational thinking and into irrational commitments. This underscores, for the secularist, the necessity of religion’s privatization, since its appearance in the public square endangers the process of rational decision making. But this characterization of the relation between reason and faith mistakes a difference for an opposition. To say that reason and faith are not the same thing is not to say that they are incompatible”that they cannot coexist, mutually support each other, and point us to the same moral conclusions about living rightly ordered lives.

As long as reason can reach moral conclusions without a sole reliance on categories of revealed truth peculiar to a specific religious tradition, acting on those conclusions cannot be called an “imposition of religion” on those outside that tradition. Instead it is to act on the basis of our best judgments about the moral life, about rights and obligations, and about how we form well-ordered relationships of family and community. These are just the things about which faith and reason both have something to say. Our modern secularists seem at times to suppose that we cannot prove we are rational unless we contradict the great moral traditions taught by religious faith. But that supposition will not bear a moment’s scrutiny. No one has yet proposed that we repeal the Golden Rule because Jesus enunciates it in the Gospels.

The rigid exclusion of religion from public life is what Judges Tauro and Walker are in fact attempting to accomplish in their same-sex marriage rulings. It is what the Hastings College of Law in San Francisco did when it refused to recognize the Christian Legal Society as a “registered student organization””the only student group ever denied this status by the college”because it requires its members to pledge their commitment to traditional Christian norms that permit sexual relations only between a man and a woman united in marriage. It’s what the Apple iTunes store did to the Manhattan Declaration, an ecumenical Christian statement defending marriage (among other things), when the group’s app for the iPhone and iPad was refused for being “offensive” to some users of the store. It’s what has happened to professors at some universities who were threatened with discipline or loss of their jobs for making statements of their moral views on homosexuality, in each case motivated by their religious faith or attempting to articulate its teachings. It’s what has happened to some justices of the peace in Massachusetts who conscientiously refused to preside over the marriages of same-sex couples and lost their jobs as a consequence. And in a truly sad story of very high social costs indeed, it’s what has happened to Catholic Charities in Massachusetts, which declined to place adoptive children with same-sex couples and has been driven out of providing adoption services altogether in that state.

It is of course the case that when religious people bring their beliefs about morality into the public square and attempt to enact them as law, it is fair to expect them to argue in terms that do not require others to share their faith commitment in order to grasp the reasons for their view. (Note that I say “to grasp the reasons,” not “to accept the reasons.” Nobody is going to concede the veto of obstinate opponents over their right even to make their argument.)

So while it is not surprising to hear religious people begin by saying, “The Bible tells us X””and it is not illegitimate for them to speak in this way”they should be prepared to give reasons that others can grasp who do not share their view that the Bible is the authoritative source of morality or who read the Bible differently. This is a Christian-majority society, but, as Denver’s Archbishop Charles Chaput said in March at Georgetown University, “We never have been and never will be a Christian confessional state.” Indeed, there are so many varieties of Christianity in the United States that any effort to behave as though we were a confessional state would only incite intersectarian conflict.

But Christians have a common language for moral argument across their sectarian differences, a language distinct from Scripture though not wholly apart from its purposes, that is also a common language of all mankind, supplying points of reference accessible in principle to anyone. This is the language of natural law, which Thomas Aquinas said is that part of God’s law for us that we can know on our own, by the use of our own reason (which He of course gave us), without any special aid of revelation, prophecy, or Scripture.

Even those who resist any notion that God gave us our reason, or that He is the source of law for us, will nonetheless admit (most of them, anyway) that we are rational creatures and that by using our reason we can distinguish justice from injustice. On that shared ground, all citizens can meet who have not made a prior commitment to the self-contradiction of relativism. But”and this is important”the religious participants in this shared deliberation on the just and the unjust are not required to stop talking about their faith or about how important it is to them. Many believers, after all, believe that their religious faith makes them better, more moral persons and better able to make useful contributions to the debates we inevitably have over public morality. Therefore our constitutional obligation to respect their freedom of speech, freedom of association, and freedom of conscience means it would be an imposition of a secular orthodoxy on them to require that they “privatize” their faith commitments and keep them out of the public square.

It is this that judges like Joseph Tauro and Vaughn Walker appear not to understand. They suggest that the appearance of religious people making religiously grounded arguments, or even arguments that suspiciously coincide with religious tenets”such as the view that “marriage” means “the conjugal union of a man and a woman””is grounds for concluding that a covertly “theocratic” agenda is at work. Again a faulty form of logic is employed, taking a form something like this: The public policy being challenged in court holds that marriage can only be between a man and a woman; traditional Christianity holds that marriage can only be between a man and a woman; therefore this public policy is an expression of traditional Christianity.

But (the argument goes on) the expression of traditional Christianity is either a) an imposition of religion on others in violation of the separation of church and state or b) the expression of a “private” moral view that is essentially “irrational,” whereas all valid legislation requires a “rational basis.” (This last step was the view of Judge Walker in the California Prop. 8 case, and substantially the view of the Iowa Supreme Court when it ruled in favor of gay marriage in 2009.) Under the sway of this error, we are in danger of telling many millions of our fellow citizens that they may not act as their conscience guides them in exercising the fundamental right of self-government.

Yet another danger may await us in the event that traditional views of sexual morality are overthrown and same-sex marriage is established. We see a sign of it in the driving of Catholic Charities out of adoption services in Massachusetts. The freedom to participate fully in civic life, to offer oneself to others in civil society, conscientiously on one’s own terms as a religious person professing one’s beliefs, may be jeopardized by this new dispensation.

A story from England sounds the warning bell. In the city of Derby, a couple named Owen and Eunice Johns applied to be short-term foster parents to children in need of a home. Having experience with foster care in the 1990s but not having done it for a while, they applied once again to be foster parents in 2007. What had changed in the intervening years was that now the standards applied by public authority insisted that all foster parents must commit themselves to “valuing diversity” with respect to sexual orientation as well as other characteristics. The Johnses are Pentecostal Christians and, when interviewed by Derby social workers, declined to compromise their religious views. As Mrs. Johns said, “I will not lie and tell you I will say it is okay to be a homosexual. I will love and respect, no matter what sexuality. I cannot lie and I cannot hate, but I cannot tell a child that it is okay to be homosexual.”

The Johnses are clearly caring, loving people who want to help children in their community. And a community willing to meet them halfway would welcome their help, even if the prevailing norms regarding “diversity” led the social workers to take care about which children should be placed in their care. But it seems their views are too “dangerous” for any children to be placed in their care. At the end of February, the High Court of Justice, Queen’s Bench Division, ruled that the Derby City Council had properly rejected their application to be foster parents under any circumstances.

Henceforth, in the United Kingdom, couples who adhere to traditional Christian moral principles on sexuality, and who refuse to pledge explicitly that they will contradict those principles in their childrearing practices, will be considered unsuitable to be foster parents”regardless, it seems, of the sexual orientation of the children who might be placed in their care. From here it is, logically, but a short step toward saying that people holding such views on sexual morality cannot be permitted to adopt infant children. Such children might grow up to manifest homosexual desire, and the state would not wish to see them raised by parents who disapprove of homosexuality. Even heterosexual children might, by the logic of the Johns ruling, be harmed in their upbringing if they grow up to think like Owen and Eunice Johns. Therefore the safest course is to deny such people the right to adopt any children.

From the standpoint of legal reasoning, the most interesting aspect of the Johns ruling was the ground on which the High Court denied that Eunice and Owen Johns had been discriminated against because of their religious beliefs. The Court held that if we can suppose a person to be capable of disapproving of homosexual relations for a non religious reason”if we can even just imagine such a person existing as a hypothetical matter”then the person whose stated reason for disapproving of homosexual relations is religious cannot complain of having been discriminated against because of his religion. What the religious person and the nonreligious person, who both have moral qualms about homosexual relations, have in common is their opinion in this matter. That opinion”not the accidental characteristic of some of those who hold it happening to be religious”is what gives rise to the state’s condemnation.

But for the religious person who holds a traditional view of sexual morality, the holding of that view is not accidentally related to his religious faith. It is inseparable from it. Eunice and Owen Johns could, of course, disapprove of homosexuality even if they were not Pentecostal Christians. But, on their own account, precisely because they are Pentecostal Christians, they cannot not disapprove of homosexuality. From where they stand, their choice is to please God, or please the state.

Now return to the way in which opposition to same-sex marriage is increasingly treated in this country. As we have seen in rulings like that of Judge Walker in California”or the Iowa Supreme Court in 2009”the argument made against the defenders of conjugal marriage is that they want to enact a religious agenda as public policy. As religious people, we are assured, they’re entitled to think “privately” whatever they please about such matters”but not to enact their view as law because, as a religious view, it is somehow by definition “irrational.” Even the possibility that their view of morality could be rational, and be rationally accessible to people not sharing their religion, is dismissed out of hand. The moral is collapsed into the religious; the religious is declared to be the irrational; and the irrational is declared to have no place in public policy.

As we have seen, this is riddled with errors about the nature of religion and its relation to moral reasoning. But focus on the first step in this train of thought”the collapsing of moral claims into religious ones, as though we cannot imagine moral precepts other than those declared by religious authority.

The irony of the Johns ruling in England is that it moves in the opposite direction. There the judges were ready and willing to see a difference between religious and nonreligious reasons for the same view. Certainly, the judges said, it is possible for someone to hold traditional views of sexual morality for nonreligious reasons. That’s how we know that, when we encounter people with religious reasons for such views, we can slap them down and deny that we are suppressing religion!

These two arguments function like a classic pincer movement, attacking religious freedom from two sides. When the purpose is to win a victory over a majority that has enacted laws unfriendly to same-sex marriage, it is useful to deny that there can be any reason for such laws other than irrational religious commitments.

But when you have won that victory, and you hold the levers of power and public authority, and the purpose is to win the next victory over the holdouts who won’t “get with the program” because they cling to traditional beliefs about sexual morality, it is useful to affirm that of course there can be nonreligious reasons for the view they happen to hold”perhaps some garden-variety “hatred and bigotry” of unspecified origins. That’s how you can defeat the freedom of religious conscience and mop up the resistance. Sooner or later the Eunice and Owen Johnses will get with the program, if they don’t wish to wear the scarlet B for Bigotry.

It is not all that far from where we are now in the United States to the destination marked out in the Johns case in England. There are disturbing signs already that we are tending in that direction. This would seem to be because the advocates of same-sex marriage are pressing their claims in the courts of law. They have manifestly failed so far to persuade their fellow citizens in great numbers. Strong majorities in three-fifths of the American states have gone to the polls and protected traditional marriage in their state constitutions; and DOMA passed Congress by huge margins in 1996 and would no doubt win handily again if put to a vote. The victories of the gay-marriage movement have been almost entirely the work of judges.

It is no surprise that the handful of judges to rule so far in favor of same-sex marriage have uniformly employed shabby reasoning, for no sound reasoning about the Constitution will yield the desired result. But even bad logic has this characteristic: It brooks no compromise as it runs its course. Premises march to conclusions, and, even if the road goes through fallacies, they reach those conclusions, which become the new premises for marching on to the next ones. That’s how principles that began by protecting freedom of religion are converted into attacks on that freedom. That’s how the support that religion gives to morality is converted into an affirmative reason to reject that morality. That’s how people who bring the light of their faith openly into the life of the community”people like Owen and Eunice Johns”are told to take that light, put it under a bushel basket, and go away. That’s how one side in a great controversy about the future of our society gets told that its view amounts only to “hate” that deserves no hearing in the public square.

In the end, this strategy pursued by the advocates of same-sex marriage will be self-defeating. That final defeat, no doubt, will not come without a struggle, displaying more of what we have seen already from these advocates: sloppy reasoning, resort to undemocratic tactics, and animosity toward religious freedom and conscience. No movement claiming to stand for human rights in American history”with the possible exception of the “reproductive rights movement””has so plainly set itself on a collision course with the moral and religious sentiments of the majority. That majority will not, I think, be argued out of the faith of its fathers and mothers and the historic commitment of that faith to the preservation of the family and the institution of marriage. Nor will it be intimidated out of it, even by the august authority of judges claiming to speak in the name of our Constitution.

Matthew J. Franck is director of the William E. and Carol G. Simon Center on Religion and the Constitution at the Witherspoon Institute in Princeton, New Jersey.