Fact: If you're against gay marriage, you're a bigot.
Fact: If you're against gay marriage because of your religion, then you're a bigot, your religion is bigoted, and you don't know how to think for yourself.
I'm against gay marriage on religious grounds and I'm nowhere near what you would call a bigot. If you think that gay couples shouldn't have the same rights as straight couples, you are bigoted against them, regardless of your reason.
I would think your argument would be that it's ok to be bigoted against gays, not that it's not bigotry?