Godless Heathens That Go Around Getting Hitched

I have a serious question for anyone that is against gay marriage for religious reasons: Why aren’t you trying to suppress atheists from getting married? After all, there are millions of gay people that actually believe in God (even the same one as you), but you don’t want them defiling the church through unholy matrimony. Meanwhile there are millions of godless heathens that go around getting hitched (even in your churches) in direct opposition to your beliefs, but I can’t recall one piece of legislation designed to deny non-believers the same rights as you want to deny homosexuals.