Metaphysical Confusions

I've noticed that the arguments against gay marriage routinely confuse metaphysical facts with man-made facts. Case in point:

Gay marriage, gay marriage, gay marriage. I don't think I've ever written a column on gay marriage. Perhaps I should. Trouble is, I can't get my mind around it. In this zone, I am totally a dinosaur. When I hear people talking about gay marriage, it falls on my ears as if they were saying: "OK, from now on, we are going to have Mars revolving round the Sun in Venus's orbit, and Venus in Mars's." Oh, are you? That's nice. But how are you going to do it? By an edict from the Supreme Court?

I suppose that religious conservatives see marriage as a fact of nature rather than a human-created social institution because God is supposed to have established it. (Then again, God is also supposed to have put his stamp of approval on slavery, the subjugation of women, and many other delights conveniently forgotten.) In any case, the appeal to God doesn't make the argument any less stupid.