I think that’s an excellent question. My answer is what he’s always been rethinking and what the emerging church is reimagining/repainting–the Gospel itself. This piece from World Net Daily reminds us of the upchucking upcoming ReThink fiasco:

It’s an all-star conference set for the Crystal Cathedral in Garden Grove, Calif., Jan. 17-19. Former President George H.W. Bush will speak. Chuck Colson will make a presentation. Larry King will be there. Rupert Murdoch will address attendees. Ben Stein will appear.

And Kay Warren, wife of Saddleback Church mega-pastor Rick Warren, will join Robert Schuller, the white-haired, bespectacled purveyor of "possibility thinking." What could such a diverse group have in common? What’s the topic? Well, it’s a little vague.

To say the least…but then in the first place that’s the whole idea behind the new evangelical and seeker-sensitive Church Growth Spiritual Dung Movement grandfathered by Robert Schuller, isn’t it? Can you say: Bait and Switch? I knew you could…

See also: Laughing at Today’s "Buzz" 

Robert Schuller: Father of the New Reformation

Robert Schuller Mentor to Rick Warren on the Love of Man: Christ Died for Negative Self-Image