A Gallup Poll published in August 2011 showed the views of members of different religious communities to the question of whether terrorist violence is ever justified. Nearly nine in 10 Muslim Americans said violent attacks on civilians are never justified, the highest level of disapproval among the groups surveyed.

Read an October 5, 2011 NPR story about a controversial book by Ken Ballen, Terrorists in Love: The Real Lives of Islamic Radicals. Ballen spent five years interviewing more than 100 Islamic extremists to learn what motivated them to carry out violent attacks against the United States and others they considered enemies of Islam.

Read an article about the massacre in Norway in July 2011 by anti-Islamic extremist Anders Behring Breivik, who claimed to be a Christian crusader even as he rejected central Christian beliefs, which highlighted the phenomenon of right-wing violence.

Faheem Shuaibe is the resident imam of Masjidul Waritheen, an affiliate of W. Deen Mohammed’s group, in Oakland, Calif. His website contains his teachings.

Megan Reid is an assistant professor of Islam in the school of religion at the University of Southern California in Los Angeles. She researched an article on the first African-American Muslims to make a pilgrimage to Mecca in the 1930s.

Robert Muhammad is minister of Muhammad Mosque No. 45 in Houston, an affiliate of the Nation of Islam, and founder of ActionCDC, a nonprofit that works to establish community housing and other programs.

Richard Brent Turner is a professor of religious studies at the University of Iowa in Iowa City, where he teaches a course titled “African American Islam in International Perspective.” He wrote an article titled “Mainstream Islam in the African American Experience.”

Debra Mubashshir Majeed is an associate professor of philosophy and religious studies at Beloit College in Beloit, Wis. She has written about Clara Muhammad for the Encyclopedia of Women and Religion in North America (Indiana University Press, 2006).

Claude Clegg III is a history professor at Indiana University in Bloomington. He wrote An Original Man: The Life and Times of Elijah Muhammad (St. Martin’s Press, 1997).