If they don't want a gay marriage then they don't have to get one. It's as simple as that. If it goes against their religion, making a law based on that is forcing their religion on others, and it goes against the 1st amendment of the U.S. constitution. We have freedom of religion in the U.S., which includes freedom of non-religion. So doing that is anti-freedom of religion. Hindu, Buddhist, and Muslim marriage is against Christianity, and yet they are legal in the U.S. Gay marriage will only be legal in the same way the marriages of those other religions are legal.
This is a win for freedom! Also the live, and let live philosophy!