I have no intention of "mocking" a God I disbelieve in. "This" life is the only one I perceive as being real. And I do not see why your beliefs concerning God, morality and the afterlife should overrule mine, when the issue in question affects my life, and not yours.
I understand that you are concerned about people who, in an environment where being gay is legally equivalent to being straight, would choose to live in accordance with their orientation, rather than trying to change it. But that will be <I>their</I> choice -- just as it is now.
They will not be forced to choose gay marriage, simply because it is available to them. They will still be able to act in accordance with their own religious beliefs. But if gay marriage is unavailable, then those who <I>would</I> choose it will continue to be limited by other people's religious beliefs, even if those beliefs contradict their own.