The idea … that marriage is an indissoluble bond between two people (and a man and a woman at that) has the imprimatur of that other non-PhD theologian, Jesus of Nazareth. And yet in today’s world, it is a political—that is, a conservative, that is, a retrograde—position. All good people know that marriage is just what you want it to be. That’s not political, that’s just common sense. It’s what everybody I went to college with thinks, ergo it must be true.
I happen to be quite well-informed theologically. I studied it for four years. I've read my Karl Rahner and Romano Guardini and quite a few others besides. A degree in theology is no qualification for sainthood and it is sanctity Christians are supposed to be aiming at. I would call the people who signed the letter denouncing Douthat horses' asses, but that would be an insult to horses and their haunches (I used to do the racing charts, so I have a certain appreciation for equine grace and beauty, thing sorely lacking in academe these days).