The Tenacity of Unreasonable Beliefs is a passionate yet analytical critique of Jewish, Christian, and Muslim scriptural fundamentalists. Schimmel examines the ways in which otherwise intelligent and bright Jews, Christians, and Muslims defend their belief in the divine authorship of the Bible
or of the Koran, and other religious beliefs derived from those claims, against overwhelming evidence and argument to the contrary from science, scholarship, common sense, and rational analysis. He also examines the motives, fears, and anxieties of scriptural fundamentalists that induce them to
cling so tenaciously to their unreasonable beliefs.