To preface this, I have a sister who is a huge activist for GLBT organizations and a wife who is liberal with a capital "L" but admits in her heart she sees marriage as something between a man and a woman. I love them both very much, and have had the following conversation with both before the election. Obviously, what we now know about the election has brought this issue to the fore. My sister and my wife don't necessarily agree with me, but they understand the reasoning and I hope you will too. That being said, here's my argument. We shouldn't be pushing for gay "marriage," even though it's what justice demands. Civil unions are likely the only way to provide equal rights and also not divide this country along religious lines.
My logic is simply that most of the country is obviously not ready for a same sex union to be called a "marriage." But most Americans are also not bigots, and I'd like to think that, if many of them are uncomfortable with homosexuality (it's icky or not something they like to think about), they are not overtly homophobic (thinking that gays are somehow less than human or less deserving of goverment protection and recognition). Polls show americans, by and large, support partner rights for same sex couples (inheritance, health proxy, etc.) but not "marriage." I used to listen to the right-wing talking heads argue against gay marriage by saying that it would take away people's right to define marriage and I'd fume -- imagine taking someone else's civil rights for your right to think the way you want to! But there is a distinction between partner rights and the definition of marriage. These are two separate things -- the first is a legal and recognition issue, and the second is a cultural and religious issue. Savvy Republican puppet-masters (ie Rove) know this, and they know they can't win the first argument. There are too many civil rights precedents in American history and in prior legal battles for them to oppose granting partner rights to same sex couples, not to mention libertarians and non-fundamentalists in their own party who'd balk at denying rights to anyone. But there isn't similar support for calling same sex unions "marriage," and making them indistinguishable in name to opposite sex unions. That is why the right wing machine, in its mastery of using language to polarize, accepted framing the question around "gay marriage" and why most of the referendums were phrased on how to define marriage and not how to distinguish who gets partner rights. Just the term "gay marriage" is abhorrent to many, even those who see no problem with what two individuals do behind closed doors, and what happens to them legally when they get sick or pass away. The right wing accepted language they know would polarize, and the left went along with the "gay marriage" paradigm to their own detriment.
And this is where a choice has to be made. My sister, the GLBT activist, has made a strong choice, that she wants "marriage," plain and simple, exactly like everyone else has, and she won't back down or accept anything less than that. And she's right to want that, same sex couples deserve that. But minds need to be changed, and let's face it, a lot of minds have to be changed before America as a whole will accept that. It has to proceed in steps. The first step is legal recognition -- "separate but equal" is a dirty phrase from American history, but if civil unions are what it takes to get partner rights for same-sex couples, then minds will start to get changed once people see that civil unions did not bring the wrath of God down, and in fact has made same sex couples seem that much more "normal." This is not a political notion, just a way to get justice for same sex unions while not perptuating any "culture war."
Personally, I think the only true legal hurdle that exists in American opinion right now is opposition to adoption by same sex couples. This is where the fight should be being waged, not on forcing "gay marriage" down the throats of those unable to deal with it, but getting the rights in place and fighting for the rights themselves and not the label. Adoption is the key because there are many who still oppose it, but can be argued for in simple legal terms. Finally, once America sees that same sex couples can not only seem "normal," but can be seen as nurturing, loving relationships from which a "normal" family can sprout, minds will be changed. Thus we should reshape the dialogue around "partner rights," including and especially adoption.