Mr. Keller is an American author, speaker, and the founding pastor of Redeemer Presbyterian Church (PCA) in New York City, New York.

Keller, once the director of his denomination's mercy ministries, has always emphasized Christian service and charity, both in his own church's members and in those the center trains to plant urban churches. Keller's book The Reason for God: Belief in an Age of Skepticism was named Book of the Year for 2008 by World Magazine, a conservative evangelical news magazine. It rose as high as #7 on the New York Times Non-Fiction Best-Seller list in March of 2008.

Tim Keller visits Google's Mountain View, CA, headquarters to discuss his book, "The Reason for God." This event took place on March 5, 2008, as part of the Authors@Google series.