Bryan Chapell is the senior pastor of Grace Presbyterian Church (PCA) in Peoria, Illinois. He is also the host of a daily half-hour radio Bible teaching program, Unlimited Grace, and the founder and chairman of Unlimited Grace Media (unlimitedgrace.com). Bryan previously served as the president of Covenant Theological Seminary in St. Louis, Missouri, and is the author of a number of books, including Holiness by Grace.

D. A. Carson (PhD, Cambridge University) is Emeritus Professor of New Testament at Trinity Evangelical Divinity School, where he has taught since 1978. He is a cofounder of the Gospel Coalition and has written or edited nearly 120 books. He and his wife, Joy, have two children and live in the north suburbs of Chicago.

Timothy J. Keller is the founding pastor of Redeemer Presbyterian Church in New York. He is the best-selling author of The Prodigal God and The Reason for God.