It’s what President Obama says is at the root of his endorsement of same-sex marriage that I call into question. It’s his invoking the golden rule. For important a value as treating others the way you would want to be treated is, it’s not really at the root of a scriptural perspective on marriage. What’s at the root is:

Then the Lord God said, “It is not good that man should be alone; I will make him a helper as his partner.” … So the Lord God caused a deep sleep to fall upon the man, and he slept; then he took one of his ribs and closed up its place with flesh. And the rib that the Lord God had taken from the man he made into a woman and brought her to the man. Then the man said, “This at last is bone of my bones and flesh of my flesh; this one shall be called Woman, for out of Man this one was taken.” Therefore a man leaves his father and his mother and clings to his wife, and they become one flesh. (Gen.2:18, 21-24)