Just wanted to add that I think more harm than good is usually done by the kind of criticism that has been reported here. "The Gospel is about redemption, not life's purpose" is false dichotomy at its very worst. Life's purpose is redemption, and redemption's purpose is that we have "life more abundantly".
Christ told us that there is a place for ignoring the tares, for fear of destroying the wheat as well. Unfortunately the church continues to miss this important lesson. If MacCarther had merely added greater theological depth to the base that Warren had laid, I would applaud his actions. But at least as it's reported here, he went beyond that, into criticism. Biblical scholar, theological wiz, or not, that is very unfortunate. The kingdom of God is about far more than theological exactitude.
Paul_B, you have spoken more clearly on this than anyone. Great!