The Rev. Maria Erling is a Lutheran pastor and an associate professor of the history of Christianity and global missions at the Lutheran Theological Seminary at Gettysburg in Gettysburg, Pa. She contributed a chapter on mainline Protestants in New England to Religion and Public Life in New England: Steady Habits Changing Slowly.

John L. Jackson Jr. is the Richard Perry University Professor of Communication, Africana Studies and Anthropology in the Standing Faculty of the Annenberg School for Communication and the Standing Faculty of the School of Arts and Sciences at the University of Pennsylvania. He has researched the beliefs and practices of Black Hebrews.

Read the Philadelphia grand jury findings and accompanying report after the case of a Philadelphia clergyman’s sexual misconduct . The archdiocese hired a former sex crimes prosecutor to review the personnel files of all the priests named in the grand jury’s report, and in March 2011 the archdiocese placed 21 priests on administrative leave pending a final report.

Catherine Warrick is an assistant professor of political science at Villanova University in Villanova, Pa. She teaches a course in Middle East politics, and one of her areas of research and expertise is comparative politics in the region.

The Rev. Kent Berghuis is senior pastor at First Baptist Church of Oklahoma City, and an affiliate in theology at Palmer Theological Seminary in King of Prussia, Pa.

Pastor Herb Lusk is a former Philadelphia Eagles tailback who is thought to be the first NFL player to kneel and pray in the end zone after scoring a touchdown, in 1977. Since 1982 Lusk has headed the congregation at the Greater Exodus Baptist Church in Philadelphia.

Nicholas P. Cafardi is a leading experts on the Catholic Church’s response to abusive clergy and an expert on canon law. He is an attorney with Cafardi Ferguson Wyrick Weis and Stotler in Sewickley, Pa.

Michael Radu is co-chairman of the Center on Terrorism, Counter-Terrorism and Homeland Security at the Foreign Policy Research Institute in Philadelphia. He has studied terrorist groups around the world and is an expert on terrorism and extremism in Turkey.

The U.S. Army Peacekeeping and Stability Operations Institute at the U.S. Army War College in Carlisle, Pa., does research and training on peacekeeping.