Timothy Keller is the New York Times bestselling author of The Reason for God, The Meaning of Marriage, The Prodigal God, Jesus the King, and The Prodigal Prophet. R. Albert Mohler Jr. has been called "one of America's most influential evangelicals" (Economist) and the "reigning intellectual of the evangelical movement" (Time.com). The president of the Southern Baptist Theological Seminary, he writes a popular blog and a regular commentary, available at AlbertMohler.com, and hosts two podcasts: The Briefing and Thinking in Public. He is the author of many books, including We Cannot Be Silent and The Prayer that Turns the World Upside Down, and has appeared in the New York Times, the Wall Street Journal, USA Today, and on programs such as NBC's Today, ABC's Good Morning America, and PBS NewsHour with Jim Lehrer. He and his wife, Mary, live in Louisville, Kentucky. J. I. Packer (DPhil, Oxford University) is a member of the board of governors and professor of theology at Regent College. Robert W. Yarbrough (PhD, University of Aberdeen) is chair and professor of New Testament at Trinity Evangelical Divinity School. Christopher W. Morgan is professor of theology and dean of the School of Christian Ministries at California Baptist University in Riverside, California. Author/editor of ten books and a teaching pastor of Helendale Community Church, he and and his wife, Shelley, have been married for twenty years and live in Helendale, California. Robert A. Peterson was professor of systematic theology at Covenant Theological Seminary in St. Louis, Missouri. He is author or editor of twenty books, including Salvation Accomplished by the Son: The Work of Christ (Crossway, 2012), Our Secure Salvation: Preservation and Apostasy (P&R Publishing, 2009), and, coedited with Christopher Morgan, Hell Under Fire (Zondervan, 2004).