A state-sanctioned union is called a 'marriage' but it has nothing to do with religious rules. It is merely a business relationship, as there is no punishment for breaking the vows.

If you want a state-sanctioned joining, everyone should get a civil union which allows them all the privileges associated with today's "marriage". If the religious want to inject their god beliefs into it, they can get an additional, non-legally-binding, ceremony at a tax-exempt church. You're welcome.