Warren's 2001 book, The Purpose-Driven Life, is this decade's best seller with 19.5 million copies sold so far and compiling at the rate of 500, 000 per month.
Warren, who founded Saddleback with his wife 33 years ago, gave the invocation at President Barack Obama's 2009 inauguration and penned "The Purpose-Driven Life, " a Christian self-help guide that became a mainstream best-seller.