The civil recognition of marriage extends as far as property rights and the certification of a social relationship oft used by insurance companies and hospitals. To elevate one functionally indistinguishable relationship over another, is legally imprudent and serves only to cement a primitive notion that same-sex relationships are inferior to different-sex relationships. That concept is allowable in private religious matters and in religious certifications, but is inappropriate as a statement of the law.
Let "marriage" be marriage as seen by each certifier and let "civil union" be its universal legal analogue.