One of my co-workers is working on his doctorate of theology. I asked him about the Landmark Forum and Sandy. This is how he responded...

Wow -- I looked at their "syllabus." That may be the oddest combination of self-help and poststructuralism that I've ever seen. (Actually, the only such combination that I've seen; but it's still pretty odd.)

At seminary they teach us to be wary of giving advice -- we're supposed to operate on the assumption that most people already know the answers to their problems, they just might need some help drawing it out. In that spirit, I think your statements that you can't make your friend "normal" again (and I would agree with that; you can't "fix" people, they have to fix themselves) and that you don't want to just cut him loose, imply your answer: the third option is to put up with it.

At the risk of slipping into advice-giving, my experience suggests that there's a decent chance he'll get over it -- it sounds like right now he has the fervor of a new convert; that usually fades over time. And who knows, he might actually retain something valuable from it -- most of these programs have some good insights buried in all of the hype. If you ride it out, I think there's a good chance you'll get your friend back again. And if not... it was his choice, not yours.