From the New York Times article, Prisons Purging Books on Faith From Libraries:
Behind the walls of federal prisons nationwide, chaplains have been quietly carrying out a systematic purge of religious books and materials that were once available to prisoners in chapel libraries….
Traci Billingsley, a spokeswoman for the Bureau of Prisons, said the agency was acting in response to a 2004 report by the Office of the Inspector General in the Justice Department. The report recommended steps that prisons should take, in light of the Sept. 11 attacks, to avoid becoming recruiting grounds for militant Islamic and other religious groups. The bureau, an agency of the Justice Department, defended its effort, which it calls the Standardized Chapel Library Project, as a way of barring access to materials that could, in its words, “discriminate, disparage, advocate violence or radicalize.”