But even if we or an angel from heaven should preach to you a gospel contrary to the one we preached to you, let him be accursed. As we have said before, so now I say again: If anyone is preaching to you a gospel contrary to the one you received, let him be accursed. Galatians 1:8,9 ESV
Paul knew the true gospel was worth defending. Immediately after this text he states that he is pleasing God in preaching the true gospel. Others who don't are only man-pleasers.
I have warned about Rick Warren's false gospel in the "40 Days of Purpose" video for about 3 years now. See brief article here. And I have also briefly reviewed the first seven chapters of his PDL book here.
A few books have been written on the subject but very few "visible" ministries on the American church scene have "bothered" to defend the gospel. Of course, men like Dr. John MacArthur would be exceptions.
This dear sister in Christ - Tamara Hartzell - has taken the time to do a major online work about Warren's false gospel. This is very excellent and comprehensive. It is titled "In the Name of Purpose: Sacrificing Truth on the Altar of Unity." I have linked you to the introductory page. The complete online e-book is under "books contents" on the left side of the page. It is here.
Committed to the gospel,