I must admit that I'm not altogether happy with gay marriage myself. Civil partnerships, which give them all the rights of married couples, by all means; and if civil partners want to call themselves married, no-one's stopping them - but men and women are designed (or have evolved) to complement each other in a way that two men or two women can't. That doesn't make gay relationships sinful, but it does make them the exception, not the rule, and completely equating heterosexual relations and homosexual ones is a step too far.