You hit the nail on the head with marriage definitions.

A bigger problem, not admitted by the religious side of this debate, is that the legal definition of marriage is what grants many states rights. To some extent that some states would have to rewrite their constitutions to no longer honor marriage as an institution.

I don't think the end game legally would end very well for the people stating that "marriage" is a religious term. It might be in common speech, but given we're talking about granting legal rights its about as relevant as ice cubes to an eskimo. Push this matter too hard and its likely that marriage as a legal term or definition goes away entirely.

I'm all for it but pushing the religious points too far will only cause more issues for those fighting via that angle. (no i'm not a lawyer)