In a perfect world, in other words heaven, there is no need of marriage for the reason that a person is in him/herself complete. In the real world however, because human beings are “broken” and “wounded” the need for an other who’s more or less a permanent presence in one’s life is as vital as air, water, and food.
Brokenness is part and parcel of being human. When God became man and lived among human beings, He did not use His “magic” to put an end to this brokenness. In fact, he partook of it as for instance societal norms and limitations at the time (e.g. Church laws, gender inequality, discrimination). I read that if He were to send everybody to who knows where for the slightest mistake it’d be as if He is negating His own Being which is that Who Is Compassion and Love. His being nailed to the Cross is symbolic of His irrevocable oneness with the human experience at the same time it’s Hope, Conscience, and Redemption.
Same sex marriage is a human experience which I believe God would be the last to condemn if at all. I believe that He patiently looks upon this experience with infinite compassion, and that ever respectful of free will and confident of human capacities He is confident the human community will resolve the issue and decide accordingly. This ought to be the spirit of the debate.