Deadite: you say it's "none of your business" if two consenting adults want to get married. But there are problems with this. The first is that this argument is about whether or not this is true; no purpose is served by merely asserting your conclusion. The argument that gay couples should be allowed to marry because it's none of your business if they marry is a clearly circular one.
The second is that, if the government is going to be involved in the issue of marriage at all, then it's every citizen's business. You are free to call their stance bigoted, foolish, inconsistent, whatever. Then we have the cultural debate. But you can't dismiss it out of hand, as if the mere raising of the issue is somehow out of bounds. Everything the government licenses and regulates is all of our business, collectively.
The third is that you keep saying that "two" adults should not be stopped from getting married. Why only two? It seems an entirely arbitrary number. The principles you've offered in support of gay marriage logically apply just as much to polygamy. Now, I rather expect that you probably
do support polygamy, but given that far fewer people support polygamy than support gay marriage, this is a hugely important implication.
The fourth problem is a very large one. You say it's "none of [our] business" if two consenting adults want to get married. And I know why you make this argument: it's a powerful one. It's particularly powerful in American politics, where the default position is to let people do what they will and only intervene when it can clearly be shown to harm others. That's a good general principle, and it's embedded deep in our culture's DNA. It's a potent framing of the position.
However, there's a problem with this argument: it's completely false. And I don't mean it's false in a vague "we all have an interest in preserving cherished institutions" way (though that's not nothing). I mean it's
literally false. The makeup of our current anti-discrimination laws puts the lie to it; a Christian wedding photographer who refused to photograph a gay wedding
was sued for discrimination (and lost!). And this in a state where gay marriage isn't even legal, mind you. The legal reality here simply does not allow for the "none of your business" argument.
Having made those arguments, I'd like to pose a few questions, if I might:
1) How do you distinguish between gay marriage and civil unions? I think it's pretty clear that the state, not being religiously-oriented, must agree to recognize some form of civil unions. Is this what you mean by "marriage"? If not, aren't you essentially advocating that the government grant the rights that most people support (even many of those against gay marriage), but that they officially use the word "marriage" to describe it? If so, why? Should the government be in the habit of defining words for us, as opposed to merely protecting rights? If there is little to no legal difference, then the issue is clearly one of social acceptance, which you certainly can't force through judicial or legislative fiat.
2) Please define the word "bigot."
3) If your position is that we have no right to prevent anyone from getting married, why doesn't that extend to the entire practice of marriage licensing? If they have no business restricting such things, what business do they have licensing them at all? Everything else the government licenses, it does for the express purpose of allowing some people to do something, but not others. Instances in which anyone can do something without restriction don't need to be licensed at all.
I have more, actually, but this post is enough to nudge the conversation in a useful direction, I think.
Closed Thread
Because my Father is a Catholic and my Mother is Church of England (That cracks me up! 
