“But government does recognize legal marriages.”
Has that been good or bad for the institution? Do you think that it is good that most folks accept that marriage can come from the gubberment? Folks don’t respect marriage because they have the idea that it is only a wishy-washy gubberment contract that can be broken and resumed with others at will.
I bet that if marriage had been left as a purely religious institution the number of folks willing to accept that “gay marriage” is possible because gubberment says so would be vastly reduced.
Freegards
I respectfully disagree. I have no doubt there would be all manner of "churches" performing homosexual "marriage" in the scenario you propose, which is basically the same as what Bokababe suggests. Besides, yours is a hypothetical approach that has already been superseded by reality (government is in the marriage business, and there will be no getting it out), so it is a pointless exercise in speculation at this point.