This argument has nothing to do with religion.

The United States of America was founded on the principles of a speration between church and state precisely because those first europeans to travel to the new world were looking to escape the oppression their religious societys had placed upon them. In the proud tradition of this country all people should be free of religious oppression. If you choose to have your legal state marraige affirmed by your choosen religious body, no one will stop you. But, do not let your choosen religious beliefs stop someone from entering into a legal state contract of marraige.