Hybels interviewed Stearns, president of the relief organization World Vision, during two April 26 services at the South Barrington, Ill., church.

Calling it "one of the finest books I've ever read," Hybels coordinated the bulk order from Nelson--who ordered an extra printing--along with sending an additional 6,000 copies of the book to Willow Creek Association pastors.

Emily Sweeney, Nelson's director of marketing, spiritual growth and practical living, said there are more than 100,000 copies of the book in print--released in March--and the company is seeing a bump in sales from the word of mouth generated by Willow Creek.

"We have definitely seen a spike this week as word begins to get out both from the Willow Creek weekend and the continued marketing efforts," she said. "Although it is too early to definitively see the response at retail, online orders are up significantly. This shows once again that exceptional content and strong word of mouth are what truly drive sales for every channel."