Conor Friedersdorf argues that that gay marriage should be culturally acceptable to those currently opposed because it will help to create and communicate a more pro-marriage, pro-monogamy society. That's a good point, but I think it reinforces a problem we have in the gay marriage debate - that is, the distinction between the religious conception of marriage and the legal construct of marriage. A couple years back, I made the libertarian argument for gay marriage, based on this distinction. With some minor changes, I'll reproduce that here...
That distinction — the sometimes invisible line between civil and religious law — is the problem; especially when the two are conflated. There is certainly some correlation between legal and moral, but immoral is not equivalent to illegal, nor is moral necessarily equivalent to legal.
Consider: gambling, premarital sex, drunkenness and gossip are immoral in the judeo-christian moral system, yet no libertarian (and very few conservatives) would criminalize them. On the other hand, there's nothing immoral about driving 45mph in a 35mph zone or crossing a national border without authorization. Yet only an anarchist would eliminate all traffic or immigration laws.
Clearly, there's no direct, inherent connection between legality and morality, and leaving aside outright anarchism, there ought not be.
This notion that the civil law ought to be distinguishable from moral law might be a bit disconcerting to those who consider their moral values inextricably linked with their political values, but it need not be. John Locke — perhaps the philosopher most responsible for the 'natural law' philosophy of our founding documents — argued that there were three kinds of "laws that men generally refer their actions to, to judge of their rectitude of obliquity".
1. The divine law.
2. The civil law.
3. "The law of opinion or reputation, if I may so call it."
Of Divine Law, Locke wrote, "men judge whether their actions are sins or duties"; of Civil Law, "whether they be criminal or innocent"; of the Law of Opinion, "whether they be virtues or vices."
If we assume — arguendo, in order to respond directly to the opposition's argument — that homosexuality and gay marriage are contrary to God's Law, then we have a classic conflict of Divine Law, Civil Law and the Law of Opinion. Extending "marriage' to homosexual couples is against divine law, but failure to do so violates our civil law of equal rights, and public opinion is mixed.
So, let's dig down a bit on those conflicts.
If we want to follow Locke's distinction between God's Law (Divine), Man's Law (Civil) and peer pressure (Public Opinion), we need to distinguish between the partnership sanctified by a Church ("Religious Marriage") and the interpersonal contract recognized by the State ("Civil Marriage").
We might call them "Holy Union" and "Civil Union". These are not the same things.
Religious Marriage, according to the various institutions that conduct it, carries with it certain specific moral duties and meanings. Civil Unions, defined by law and enacted by State institutions, carry very different meanings and obligations. Nowhere in the Bible can I find any reference to religious marriage requiring "status as next-of-kin for hospital visits and medical decisions", or "judicial protections and evidentiary immunity".
Yet, with no religious basis at all, we've incorporated those benefits into civil marriage. How can we still argue that civil marriage is equivalent to religious marriage. We have conflated two separate modes of law, in the process introducing religious judgments into civil law. Therein lies the fault: as Locke had it, peers enforced the Law of Public Opinion, "politic societies" (i.e., properly enacted government) enforced the Civil Law (which consisted of protecting "life, liberty and estate"), and God enforced his own law.
But we've confused them, as if a God somehow requires the assistance of politicians.
From a libertarian standpoint, the fact that civil and divine marriage share the same name is irrelevant. They are separate and distinguishable. No religious person is obligated to accept a Civil Union as a Holy Union, nor are the non-religious obligated to accept a strictly Holy Union as a Civil Union.
The ideal libertarian solution would be to have the government get out of the 'marriage' business altogether; to have government enforce civil contracts, and to have religions perform their religious ceremonies, if and how they choose to do so.
But since we don't live in Libertopia, we're left with a purely civil legal privilege available to one set of people, but not to another set, simply because that civil legal privilege arose from a religious ceremony. At least, within our cultural heritage; among some other cultures, marriage had little to do with religion. If those who object to gay marriage on religious grounds would be consistent, then let them also reject the civil privileges of marriage not contained in the Bible.
Until such a time as we could clearly distinguish the two in legal terms, however, the civil legal privileges of marriage should be extended to everybody.