Spiritual conflict with Islam has a long lineage in Christian thought. Bernard Lewis, the dean of Western scholars of Islam, points out that the two faiths have so much in common that they are natural opponents. Each conceives of itself as exclusively bearing God’s final message to the rest of mankind, correcting or completing prior beliefs. In addition, many adherents on both sides believe that the world is in the last stage of a millennial struggle. These parallels inevitably lead to hostility, says Lewis, and that is the real clash of civilizations.