Not sure if I understand all of this but:
If a ‘church’ unites a man and woman in marriage, then isn’t that a God thing? That is what ‘church’ is all about right?
If a ‘courthouse’ per say unites a man and a woman in marriage isn’t that a ‘contract’ thing and it becomes a ‘state’ thing? Isn’t that what States do, contracts?
That is pretty much it.