Timothy J. Keller was born in 1950. He received a B.A. from Bucknell University in 1972, a M.Div. from Gordon-Conwell Theological Seminary in 1975, and a D.Min. from Westminster Theological Seminary in 1981. He was ordained by the Presbyterian Church in America and served as a pastor in Virginia for nine years. He is founding pastor of Redeemer Presbyterian Church in New York City, New York. He has written several books including Grace Changes Everything, Generous Justice: How God's Grace Makes Us Just, and The Reason for God: Belief in an Age of Skepticism, which won awards from World Magazine and Christianity Today.
Mark Ashton (MA, Oxford University; MA, Cambridge University) is vicar of the Round Church (Anglican) at St. Andrew the Great, Cambridge, England.