Robert Royalty is an associate professor of religion at Wabash College in Crawfordsville, Ind., where he teaches a course titled “Apocalypse Then, Apocalypse Now,” which looks at the history of apocalyptic movements and groups from Rome to Waco.

John Byron is associate professor of New Testament and Greek at Ashland Theological Seminary in Ashland, Ohio. He has written about evangelical fascination with the Rapture on his blog The Biblical World.

J. Daniel Hays is a co-author of the Dictionary of Biblical Prophecy and End Times. Hays is on the faculty of Ouachita Baptist University in Arkadelphia, Ark.

J. Scott Duvall is professor of New Testament at Oachita Baptist University in Arkadelphia, Ark., where he also holds the J.C. and Mae Fuller Chair of Biblical Studies. Duvall is a co-author of the Dictionary of Biblical Prophecy and End Times.

Tim Warner is pastor of Oasis Christian Church in Tampa, Fla., and author of the website Answers in Revelation.

Thomas B. Slater is a professor of New Testament at Mercer University’s McAfee School of Theology in Atlanta. He has said that Family Radio’s billboards claiming that Jesus would return on May 21, 2011, were inherently misguided.

Dick J. Reavis is an associate professor of English at North Carolina State University. He studied the history of end-times movements while researching his book about the Branch Davidians,  The Ashes of Waco: An Investigation.

Kevin Lewis is a professor of religious studies at the University of South Carolina in Columbia. He teaches a course called “Visions of Apocalypse” and has written an essay on Americans’ obsession with the apocalypse.

Kenneth L. Gentry Jr. is an ordained minister in the Presbyterian Church in America. He is the author of several books on Revelation and lives in South Carolina.