I have not read The Shack, but I was struck by this bit from Patrick Hannigan’s review:

That said, I can’t give “The Shack” an unconditional recommendation because its craftsmanship is inconsistent and its narrow focus on healing by any means necessary leaves significant minorities of readers either adrift or trying to connect dots that aren’t there. I am a fan of the Lord of the Rings movies, and this novel’s relationship to the gospel reminded me of Gollum’s relationship to Frodo, which pinballed between dysfunction and treachery on the one hand and surprising helpfulness on the other.

Ouch.