“Marriage licensing is a relative modern concept.”
Perhaps the word “licensing” is?
But laws throughout cultures and history acknowledge the marriage relationship, as one man and one woman, and impact inheritance, bigamy, taxation, adultery, adoption, legal testimony, rape and sexual assault, power of attorney whether it is called that or not, visitation rights even as to prison and so forth, child provision responsibilities, etc.
It is a HUGE civil partnership that is unique. It is not spiritual only.
I have no problem with churches defining marriage, I have a problem with governments defining marriage.
If the government can define it as between one man and one woman, they are then permitted to define it as anything they want.
The civil union part needs to be separated from the spiritual part called marriage.