It is up to the religions of the world to decide who they allow to marry.
I agree with your comment in principle, kap, but unfortunately in practice, the "rites" of marriage have been inextricably intertwined with the "rights" of marriage. I would like nothing more than to see the Constitutional guarantee of separation of Church and State strictly observed in the matter of marriage, and I hope that the issue of "gay marriage" will ultimately provide the catalyst for the Supremes to make such a declaration.
Until then, I acknowledge that same-gendered couples are being denied the same rights as different-gendered couples and that the proper way to address that is to afford the same validity in the eyes of the law to same-gendered couples no matter what religious institution their "rites" are performed in - or none.