I've read with interest the commentary on Andrew Sullivan....When my wife and I were practicing artificial birth control I still received the Eucharist but always felt "tainted". I felt like there was something wrong, even though 80% of Catholics use the pill. Well how much worse must a practicing homosexual feel! The disconnect must be surreal, so I can understand Sullivan's desire to have the Church change. The sex drive cannot be overestimated. It is often, surreptiously or overtly, the organizing principle around which our philosophies are arranged. Thus for the person who is promiscuous the Church is, definitionally, wrong.
The problem is that we moderns cannot hold together the fact that something we do regularly could be intrinsically wrong. It's a problem with authority, naturally, but it could also be a lack of humility in not being able to say, "even if I can't personally do fill-in-the-blank, I will recognize that I am the one that is wrong and not the Church". A friend laughed when we started NFP saying, "you'll change your opinion after your fourth kid", implying not only that it wouldn't work but that we would change our minds on the rightness of it. I said that it was true, we might not be able to handle it, but that it would still be wrong. But would I? Would I give up the Eucharist in that case? I would have to recognize that I could not live up to the standards but not to move the standard. To be in the state of mortal sin is intolerable, so perhaps we would all do the same thing - find someone to tell us what we so long to hear - that we are in the state of grace.
I have much more of a problem with Garry Wills and John Cornwall and Fr. McBrien then Andrew Sullivan. They (presumably) don't have the sex drive in the way. And their credibility is higher than Sullivan's, who has honestly admitted his homosexuality and somewhat undermined his agenda. I empathize with Sullivan - he's held together somewhat fragilely. His much publicized bouts of horrible depression must make him think that sexual activity will keep those demons away.
Ultimately perhaps it comes down to a lack of trust - faith - that God will not give us more than we can handle, as St. Paul says. Second, a belief that universal norms can be held to universally. And third, the faith that even if the laws of the Church did not lead to optimum mental and physical health we still must follow. A perhaps flippant example of this last point is when my evangelical friend showed me an article which said that "looking at woman's breasts for five to ten minutes a day lowers a man's blood pressure" and promotes health, wealth, and longevity, blah-blah-blah. Well that's not an option. And besides, those studies are always wrong.