Is the gay marriage push a demand that I accept homosexuality as legitimate?

Gay marriage advocates argue that this is an equal rights issue. But what is it that a married hetero couple can "do" that an unmarried gay couple cannot "do"? Under current law, gays can commit themselves to one another... they can live together... what can't they do that married people can do? Nothing, as far as I can tell.

So why is it so important for these gay (and lesbian) couples flocking to San Francisco to be able to hold up an "official" marriage certificate after their one-minute wedding? I surmise that it's about validation: gay and lesbian marriage is about their relationship being recognized precisely as a marriage.

But my question is this: why am I being forced to acknowledge gay relationship as marriage? That is, after all, what marriage is: a political (i.e. public, on behalf of the people) stamp of recognition.

Hence, my conclusion: in many ways (albeit not for all those involved), gay marriage is about forcing the body-politic to recognize homosexual unions as legitimate.

Update: Occasional commentor Madeline comments that civil marriage is a civil right, and as such, cannot be denied to some but not to others.

My question for her and others: what exactly does the right to marry mean? How do you prove that a man has a right to marry another man? It's clearly not self-evident, and hence it must be rationally demonstrable; so... can anyone use a rational argument to prove that a man has the right to marry another man? NB: don't beg the question -- don't assert that anyone has the right to marry anyone, because that's precisely the point I'd like to see demonstrated. All of our rights are rationally verifiable... I'd like to see the rational verification of the right to marry someone of the same sex.