This is quite clear. As in many other instances, the definition of marriage that "the world" has established is vastly different from what our Creator God has designed and defined it to be. Christians can be secure in the knowledge that marriage was wisely and lovingly instituted by our CREATOR GOD. Any other definition that accommodates the "human construct" is simply the result of Original Sin, and is just one more distortion of God's intended PERFECT creation. It is not simply human intelligence that leads us to the fact that "natural law" and procreation tend to rationally define what marriage is (biologically, in the animal and homo sapien world), but it is FAITH that provides the TRUE knowledge of the love between a man and a woman that "completes" what our Wise and Loving God designed for us. When human intelligence overrides what God has designed and instituted with a "human construct", then we find ourselves back to the original question that the Serpent asked Adam and Eve when they ate the fruit of the "Tree of Knowledge"; "Did God REALLY say that?" The answer is still, "YES, HE DID;"