When public officials, religious leaders, and general zealots insist on the sanctity of marriage being supported and even included in the law of the land, they are exposed as uninformed hypocrites by the reality of the world and the history of marriage itself.
Sanctity of marriage implies some moral, religious basis for the institution. Well, in some religions it is a sacrament so marriage is considered very important. Of course this doesn’t really address the fact that a couple can be legally married totally independent from the church simply by going to a Judge, a Justice of the Peace, or the Captain of the cruise ship. Is marriage a sacrament or a legal concept? If it is a legal concept, then the State may recognize the religious marriage as if it had performed the ceremony itself. But let’s face it, the ceremony is just decoration, the signatures on a legal contract are what constitutes a marriage.
Historically, religious and civil laws have been far less separated than they are today. Marriage, as an institution, was given the sanctity of the church and the control of the civil authorities fundamentally to assure the continuance of the wealth of powerful families. If there was no strict way to tie a woman to a man, then there may be offspring that could challenge the normal inheritance path. After all, remember that marriage was fully developed in a time when women were chattel—uneducated, without any legal rights of their own.
I ran across a comment in Parade’s End that seems apropos, if a little dated:
… if it came to marriage, ninety per cent of the inhabitants of the world regarded the marriage of almost everybody else as invalid.