If gay marriage is about rights and tax laws and inheritance and the legal benefits of marriage then why not just create a duplicate of the marriage tax code and have the gay community come up with a new name that they vote on. You don't have to disrespect people who believe in marriage to get the rights you want and deserve. Respect goes both ways. Give them their rights but don't encroach upon the fundamental and thus spiritual meaning of marriage.
You say “just” as if it’s easy to create a new tax code and institution. There is no reason that the government shouldn’t recognize gay marriages. The government should be secular. If churches don’t want to recognize gay marriages, you could make the argument that they are free not to. But the government has no obligation to uphold the “spiritual”, and should be free to issue unions regardless of whether it makes priests angry.
Separate but equal has never worked in our history. Marriage can have two definitions, just like many words
I am straight, and married, but not in a church. My marriage is not religious. My pastor would not marry me and my husband and without going to counseling to force him into the same Christian sect as me (I was in an evangelical church, he was raised Catholic)
If you want the government to not use the word marriage, argue for them not to use it EVER. We can all legally have civil unions not marriages.