Christians: Why should marriage be illegal?

I think the reason most Christians dislike ual marriages is that the whole relationship is viewed as unwholesome and unproductive in the first place. Then they sully marriage, which some view as a Christian sacrament. All of this goes back to Leviticus I believe. I am a Christian in favor of gay marriage ONLY because I follow the bible. I don't judge others and I think people have forgotten about that aspect of Christianity. Also, Leviticus goes on to claim that women going through their cycle should leave the village. Anyone who wants to follow this book that closely should put their wives/daughters/mothers in the street once a month. Furthermore, the schemes which debase the sanctity of marriage are those shows who make fun of it and get-hitched quick operations like the one in Vegas. Don't blame the gays people.