You are confusing man's world [currency] with GOD's world [marriage]. Nothing to compare.
Man's world IS God's world, but God's world is not automatically Man's world.
God is not up in Heaven, a disembodied entity separate from Earth. God is part of Heaven, part of Earth, part of humanity. Our laws should be based on God's Law: nature. That is not to say our laws should be based on a singular religion, but should be based on the Tao, the natural laws that CS Lewis wrote about so eloquently, and that exist, with minor variations, throughout every culture.
Marriage is one of those natural laws. It cannot be rationalized away into a separate, private compartment of life just because you have homosexual friends/relatives who want what is unnatural.