When future historians try to explain the presidency of George W. Bush, his religious fundamentalism unquestionably will be a central focus. It has made him certain about the correctness of his policies, especially the Iraq invasion, and emboldened him to push forward where other presidents, including his father, would have been far more cautious. Few writers feel comfortable discussing this aspect of Bush because tolerance for people's religious beliefs is deeply ingrained in American law, history and culture. Implicitly, we are therefore led to accept that we cannot judge others on the basis of their religious beliefs, no matter how...