Here would be one example... These can be found by researching any of the other "Churches" too.
Catholic marriage - Wikipedia, the free encyclopedia
Again, you're clearly being purposefully ignorant or just trying to irritate. Either way, come back when you're actually interested in a discussion.
I am definitely not trying to irritate and am interested in a discussion.
I don't deny that churches have refined a concept that we call marriage, but cross culturally among many different non christian religions, the prevalent view since prehistory is some sort of heterosexual relation capable of reproduction constituted a household. I am not an expert and there may be historical evidence of a society that had a civil or religious ceremony for homosexual relationships.
As such the concept itself predates Churches and was not formed by them under some sort of religious decree.
I believe a word has meaning. Let marriage mean man/woman. Let the gay community come up with a word or phrase of their choosing and let whatever group that wishes to perform a ceremony. Don't make one religious group accept it as valid if they do not wish to do so and get government out of it (my preference). Or apply all civil advantages of the hetero to the homo sexual relationships.
If for generations the sky has determined to be blue in color, its blue, not red.
If marriage has meant man/woman for the longest time, then call the man/man or woman/woman relationship by a different word.