On Tuesday, citizens of California will have an opportunity to place our indelible stamp on the forward progress of civil rights in the United States. I’m not talking about the election of Barack Obama as president, though that certainly will result in dramatic and needed advances on all sorts of levels. Instead, I’m talking about Proposition 8, which if passed would amend the state’s constitution to add the simple, elegant, yet contemptible phrase, “Only marriage between a man and a woman is valid or recognized in California.”

What’s the big deal here? you might ask. After all, voters in 26 states already have written such restrictions into their constitutions – why not California? The difference is this: On Tuesday, for the first time, a state’s voters will be going to the polls with the power to take an existing marriage right away from same-sex couples. That is, Californians will be deciding whether to tell more than 11,000 couples who have exchanged wedding vows since last May that their marriages are no longer legally valid. Each voter’s moral and ethical decision on Prop 8 will not be made in the abstract, as those decisions were in other states, but will have real and immediate consequences.

Whatever happened to “let no man put asunder”?

Unfortunately, no one knows exactly what those consequences will be. Will all those marriages be instantly annulled? Will all those couples have to wait in limbo through years of court challenges? California’s attorney general, Jerry Brown – yes, that Jerry Brown – has said he will argue in court that marriages already performed should not be annulled. But if 11,000 gay couples in the state continue to claim a basic right that has been stripped from millions of other citizens, what will “marriage” mean to anyone anymore?

Though his logic on that issue is questionable, Brown must be congratulated for a maneuver that made passage of Prop 8 that much more difficult. Once it had qualified for Tuesday’s ballot, it became Brown’s task to create a description of the initiative that will actually appear on the ballot – and he used that opportunity to ensure that the first words voters will read about it in the booth will be, “Eliminates Right of Same-Sex Couples to Marry.” The religious groups that back the initiative – primarily Mormons and Catholics – sued to change that language, but lost. And pollsters say that when Prop 8 is phrased as an “elimination of rights,” its support drops at least three points. In a vote as close as this one promises to be, those three points could be crucial.

Dwelling on such fine semantic points seems rather tacky when we’re talking about something as fundamental as marriage rights – but then, the campaigns for and against Prop 8 have been nothing if not tacky. Proponents have cooked up ludicrous arguments designed to make the idea of gay marriage more personally repulsive to straights; they’ve claimed that public school teachers will be forced to “teach gay marriage to our children,” and that churches that refuse to perform same-sex marriage ceremonies might be sued or might lose their tax-exempt status. (A bit of logic for churches whose doctrines and congregations encourage discrimination: What makes you think a gay couple would want to have anything to do with you?)

Meanwhile, in recent weeks Prop 8 opponents have begun tying the initiative to one of its major funders, the Church of Jesus Christ of Latter-Day Saints, and asking voters, “Do you really want the state of California to subscribe to Mormon values on marriage?” Big love, indeed!

It’s understandable that a heated argument over gay marriage would take such an ugly series of turns, but that doesn’t make it acceptable. Antagonists on both sides of the issue too often take the easy way out, and accuse each other of being immoral or bigoted – making real, reasoned argument impossible. (I am hardly immune to this impulse, as I noted in a column written soon after the California Supreme Court legalized gay marriage back in the spring. And even though I recognize that people on both sides of this issue may be sincere in their beliefs, I frequently must remind myself that others no doubt find my tolerance for “homosexual behavior” and my willingness to dismiss commonly held religious beliefs just as offensive as I find their passion for denying basic human rights to a particular group of law-abiding citizens.)

Simply believing that one’s own position is the right, moral and just one is not enough. The basic question surrounding gay marriage is a constitutional one: Will the religious beliefs of one segment of our society – no matter how large or small – be allowed to dictate the laws of a diverse nation? Based on the First Amendment, the simple answer is “no” … but when it comes to politics and religion, things are never that simple. So here’s the longer answer:

The founding fathers, despite their acceptance of 18th-century societal “norms” regarding slavery and the rights of women, set up America’s civil society with the ideal of recognizing each individual’s rights equally. As the centuries have passed, our nation and its laws have advanced inexorably closer and closer to that ideal. As it pertains to gay marriage, however, our basic problem is the fact that our modern definition of marriage is really a two-part equation.

It’s a religious tradition – a practically universal one among faiths worldwide – that conforms to formal strictures beginning with a “sacrament” and continuing with a variety of moral boundaries (no adultery, “til death do us part” and all that). Of course, the sacrament of marriage long ago stopped depending exclusively upon religion for legitimacy; any Vegas wedding-chapel Elvis can tell you that.

However, marriage is at the same time a state-sanctioned (indeed, state-licensed) union that entitles those who enter into it to more than 1,000 federally recognized benefits, in addition to those offered by banks, insurers, and other private and public institutions. And currently, in 48 states at least, marriage is a right that is granted to people of one sexual orientation but not to the other, thereby excluding gays from all those benefits.

From a civil-libertarian standpoint, this situation is untenable. The state simply cannot bestow rights upon one group of citizens that it does not give to all. It’s discrimination, pure and simple, and contradicts the values of liberty and prosperity upon which the nation was founded.

So what we have here is the very definition of a church-state contradiction. Churches cannot and should not be forced to bless or recognize the marriage of anyone they choose to exclude; they’re not public institutions with legal obligations (as long as we ignore that pesky matter of tax exemptions and the responsibilities they confer), and they’re entitled to exclude anyone they want. If members of a particular church can live with their beliefs and practices, then so be it.

However, the federal government cannot be exclusionary in the same way, even if it is acting on behalf of a majority of citizens who hold such beliefs. The principles of equality and freedom are right there in the Constitution, and as we move closer to a “more perfect union,” the laws and policies that institutionalize old prejudices must inevitably fall away. If they don’t, we’ll eventually reach a point at which our “American experiment” has reached its logical conclusion, and we’ll remember it as a near-miss in mankind’s attempt to achieve equality for all.

So, then, what’s the solution to the church-state conundrum? Must the state, in the name of equality, give up the power to license and recognize “marriages,” settling instead for recognizing “unions” for both gays and straights? If we do that, then is “marriage” a status reserved for church members, thus excluding from the institution not only the fraction of the population that is gay, but also the growing percentage of married couples (like my wife and myself) who were not married in a church and/or are generally “unchurched”? And what, in that circumstance, would define a “church”? Would Elvis wedding chapels qualify?

I don’t think any of that is necessary. It is entirely appropriate for the state to define marriage broadly, while various religious faiths define it however narrowly they want; after all, the Catholic church (for one) already forbids some things that the government not only supports, but funds (family planning, for instance). As for individual beliefs … well, there’s no law against bigotry, and there can’t be. So, must all those who stand against gay marriage on moral grounds (or just because they find it distasteful) change their position? No. Must they, as citizens of a free society, stand aside and allow their fellow citizens to exert their inalienable rights as freely as they themselves can? Yes.

These are the stakes on Tuesday, as California’s religious conservatives try to write their morals (it took great restraint not to type “bigotry”) into one more state’s constitution. May they fail – and may the rest of the nation someday follow California’s (hopefully) inclusive example.