I'd say it's about time that civil partnerships with full rights and benefits were allowed for everyone and leave "marriage" as a religious thing.
If people want to cite reasons of (Christian) religion for denying gay people the same rights as straights, they should really do that across the board. The bible forbids divorce, sex outside marriage, long hair on men, short hair on women, tattoos, piercings, women wearing men's clothes and men wearing women's, eating shellfish, wearing clothes made from mixed fabrics and so on. The list is pretty exhaustive. Let them try to enforce all of those things at the same time. Oh, wait, that would have an effect on their own lives so they wouldn't want to do that. After all, how many of the well-known evangelists are still married to their first wife? How many of them eat pork?
A couple of posters have mentioned that marriage is about having children. Fine. Who's going to tell a every woman who's past childbearing or has had a hysterectomy, or is sterile for any reason that she can't marry? Or any guy who's sterile for that matter. The arguments don't add up