To clarify my earlier post...
Marriage is three things: 1) a legal contract, with legal and fiscal ramifications for parties to it; 2) an agreement which society recognises as being of a unique and institutional value; and 3) a covenant before God.
In my opinion, 1) must apply equally to all people and all marriages, and there is no overwhelming reason why homosexuals should not be able to enter into it with the person they love. There is an argument to be made that normalising same-sex legal unions may have a deleterious effect, in principle and in practice, on the well-being of children. I am not convinced by this argument, not yet at any rate, and regardless it could be resolved without imposing any limitations other than on the freedom to adopt children.
3) must be a personal choice, to interpret or disregard as one sees fit. Many religious people think that a same-sex marriage is as valid and divine a covenant as a different-sex marriage, and there are churches that will marry homosexuals. These churches may marry homosexuals qua 3) irrespective of whether the marriage is also a marriage qua 1) or 2).
My point is that same-sex civil unions satisfy equal rights and freedoms qua 1) and 3), and that if society doesn't recognise same-sex unions as marriages, then "same-sex marriage" is coterminous with "same-sex civil union." If two men or two women enjoy the legal benefits of being married, and consider themselves married before God, then I'm not sure they'll care if society doesn't say they're married. Further, I don't think there's any such thing as a right to be considered married, since that might imply a legal duty on the part of society to think something contrary to what it already thinks. I hope that we may reject out of hand any legal duty to think anything at all.
All of this being said, I would have absolutely no problem with society defining marriage so as to include same-sex unions. I think it would even be a good thing, if it makes homosexual people feel more welcome and accepted. Practically speaking, I think it would be wise to consider "a majority of society" to be roughly two-thirds for these purposes, just as in the standard rule about modifying constitutions, so that any question of vacillation or instablity would be silenced.
EDIT
Not by what aspect of the term marriage I consider quintessencial of the term. It's the desire to bind with another, of sharing a life, that I consider marriage, not the mere junction of a male and a female genitalias. Hence, IMHO, a gay couple which honestly desires to share a life are honoring the term much more than a heterossexual couple which marries on an impulse, with no real love, and divorce within 3 years.
Sure, you can value the genders as the most crucial, defining, aspect of it, if so you desire. I'll never consider that a wise choice, though.
I agree with you here, Fred. I think gender is not the single most important aspect of marriage, and if I could speak for society, gay unions would be called marriages. I'm saying though that the fact of society's refusal to recognise them as such, if a majority do refuse, renders meaningless any insistence on legally referring to gay unions as marriages. So for people such as us, same-sex "marriage" is something to support, and perhaps to look forward to, but not to insist upon by means of rights-based arguments.
Of course, Canada is moving as a society towards recognising gay unions as marriage-- I think it's presently about a 50-50 split-- so our situations are different.