Ben Witherington has the most balanced review I've seen of The Shack, including this bit on the institutional church:
There is no such thing in heaven or on earth as an organism without organization, order, structure, form, otherwise it would have no distinct shape, purpose, or being. And that applies to God, the church, as well as to all created things—remember the story of how God created the universe in a very specific order with very specific properties? Well it’s always been like that. Creativity takes a particular form and shape, bring order out of chaos or a disparate group of elements. Spontaneity is not particularly more God-like than something that was planned before the foundations of the world and executed over a long period of time. And why we should think an organism like the church needs to normally be completely spontaneous in order to be ‘alive’ is a mystery. Perhaps it is an over-reaction to spending too much time in moribund or unwell churches. One thing I know about real works of art--- they take time to create, and care, and skill, and form, and substance. This is as true of a Matisse masterpiece as of God’s creation of the universe.
I used to be drawn in by the anti-institutional rhetoric, but have since come to see that (as this quote says) organization is essential (I'd even say beautiful). However, the difference for me is between mechanistic and organic formations.
Peace,
Jamie
For all its creativity, unfortunately The Shack royaly blows and misunderstands the trinity.