Somehow, one of the most critical issues facing our country right now is the possibility that people might marry someone of the same gender. Forget unemployment, health care, or education. The real problem is that there are guys who want to marry guys.
While a few people are willing to acknowlege that they're just being mean-spirited and don't like gays or lesbians, most try to cloak their position in more "rational" arguments. These tend to fall along two lines: homosexuality is religiously or morally wrong, or gay marriage will destroy the concept of the family.
The religious argument seems to get less play. Hopefully this is because people realize that legislation resting on strictly religious grounds doesn't stand a chance under a First Amedendment challenge. It is worth noting, however, that the state can't force any church to perform a religious ceremony against that church's doctrine. That is, after all, part of the motivation for the First Amendment.
Regardless of the arguments, the motivation seems to be the same: bigotry. Claims that gay marriages are more likely to end in divorce or that gay households are bad for children are not borne out by statistics. If any heterosexual couple can go to a drive-through chapel in Las Vegas to get married on the spur of the moment, this clearly signals a greater degradation of the institution of marriage than gay marriage could ever cause.
When we speak of "marriage," we are really speaking of three separate things. The first is of a religious rite and the (supposedly) life-long bond it creates. The second is as the basis for the family. The third, and typically least considered, is a legal status. As discussed above, the religious aspect of marriage is irrelevant when considering marriage from the perspective of the state. If religion held dominance, then interfaith marriages would not be legal.
There is, of course, a historical argument for the status of marriage. It has traditionally been a religious institution sanctioned by the state, conforming to the laws of the church. We must remember, however, that the state and the church were intimately tied through most of history, so we cannot determine with any certainty what original motivation there was for marriage. We might suppose, from some ancient descriptions as well as the way that marriage is still treated in some societies, that it was essentially a way of defining property.
Marriage, as it relates to the family, has changed greatly through time. Where it was once considered the precursor to having children, it is becoming increasingly common for couples to have children without getting married or for couples to get married and not have children. Family is, after all, defined by relationships and not by ritual (the status of minors notwithstanding).
From the perspective of the state, marriage establishes a set of rights and obligations between two adults. These include tax benefits, hospital visitation rights, insurance coverage, inheritance rights, and more. These rights protect a dependant partner against the death of the primary earner; this protection is denied a same-sex partner, even when the couple would be considered common-law married if they were of the opposite sex.
The state is fundamentally incompetent to judge the quality of and commitment to a relationship between individuals. With opposite-sex couples, it takes for granted that if they are willing to testify that they're in a committed relationship, then they are. This respect is denied to same-sex couples, and is in essence an insult to same-sex couples.
The crux of the problem could be that "marriage" has too many common meanings in our society. If we used separate terms for the religious and state aspects, then perhaps gay marriage would become less controversial, at least in the realm of secular politics. This would require all states as well as the Federal Government to replace "marriage" with, say, "civil union" in all relevant laws. The acts of civil marriage and religious marriage are already distinct, and while the majority of people have both, neither requires the other.
By defining marriage and civil unions separately, more people might begin to see the injustice of denying common rights and privileges to a considerable segment of the population. At the very least, it would highlight the intolerance that underlies the opposition to gay marriage. For some people, that kind of spotlight is what is required to show them the questionable moral stances they have adopted.