The kids don't want to eat the cereal because they've heard it's good for them so the enlist the help of "Mikey" their younger brother. "Let's get Mikey" they say and sure enough "Mikey" eats it up.
Rick Warren is the Mikey of inter-faith efforts. Any time they need a Christian voice to lend support to one of these things, he's there to 'eat it up' and lend the impression that all religions are basically the same.
While Life Cereal may be good for you, allowing the world to believe that Christianity is just another religion, not all that different from any other, or that caring for the poor is the Gospel rather than a result of the Gospel most decidedly is not.