I think the unfortunate root cause in a lot of this is the duality of the word "marriage". It has completely separate legal and religious meanings that are (obviously) not necessarily in check. If you replace any reference to legal "marriage" with "marriage-legal" and religiou marriage with "marriage-religious", then I think this resolves your concern. They are different words with different meanings and different restrictions in each context. I think fukinjim is right that things would probably be a lot easier if the government just abandoned the word "marriage" in all contexts and just renamed the whole thing Civil Unions.