I can't remember who said it first, but the advice to anybody who objects to a same sex marriage is not to marry somebody of the same sex. Problem solved!
What I don't understand is the notion bandied around that allowing gay marriage would somehow devalue it for the rest of us. I'm in a happy heterosexual marriage but I wouldn't suddenly feel threatened if homosexuals had the same rights, that's a very strange idea. Furthermore I don't get the idea that gays are somehow bringing down the sanctity of marriage. Yeeeess, whereas (say) Katie Price is really showing us the way.
Most of the objections to gay marriage come from people who take a work of fiction seriously and believe in magic sky fairies. Their views really shouldn't be taken seriously. I was at a wedding earlier this year and the priest began by telling us "in this church we believe marriage is a commitment between a man and a woman" before launching into a thunderous diatribe which ended with his face turning purple. At this point all I could think was "you're wearing a dress", but I let it go...