You seem to be asserting that since marriage has been treated differently at different times, that defining it to mean something totally antithetical to its purpose is appropriate. Not only that, but you're arguing that appointed judges have some sort of supreme power to exercise this discretion. Until the recent imprinting of this particularly totalitarian strain of liberalism into our law and culture, I'm unaware of any time in Western history when same-sex "marriage" was considered acceptable. Don't you think that maybe....just maybe....we the people ought to have some say in the matter?
What is “the” purpose of marriage? Are you suggesting there’s only one?
Take another peek at the history of civil marriage, especially the precedent for judicial determinations.
Since you’re admittedly unaware of the history of same-sex marriage, here’s another useful link.
http://en.wikipedia.org/wiki/Same-sex_marriage