What I've said for some time but of course this guy says it so much better.
From TownHall and Frank Turek:
...We’re all playing by the same rules—we all have the same right to marry any non-related adult of the opposite sex. Those rules do not deny anyone “equal protection of the laws” because the qualifications to enter a marriage apply equally to everyone—every adult person has the same right to marry.
Homosexuals want the court to believe that because of their sexual desires they are a special class of persons that is being discriminated against. In other words, they think that sexual desires guarantee people special legal rights.
That’s a preposterous premise! It would mean that men born with a desire for many women (i.e. most men) are having their rights violated because marriage laws provide no means for polygamy. Likewise, it would mean that people desiring to marry their close relatives don’t have “equal rights” because our marriage laws have no provision for incest. And bisexuals could object because existing marriage laws don’t allow them to marry a man and a woman!
If desires alone guarantee someone special rights, why no special rights for pedophiles and gay bashers? The answer is obvious—because desires, even if you were “born” with them, do not justify behavior, do not make anyone a special class, and should have no impact on our laws (see Born Gay or a Gay Basher: No Excuse). ... (read it all here)