Muhammad ibn 'Abd al-Wahhab (1703-1792) aroused great controversy in his lifetime. More than two centuries after his death, he still elicits strong views. For some he is the model of a pious religious activist who fought to establish a regime of Islamic godliness in the least promising of environments. For others, especially Muslims associated with mystic orders or who belong to the Shi'i branch of Islam, he is a hate figure. Few would contest that he shaped the Muslim world. For over 250 years the Wahhabi movement has rested on the twin pillars of a clear, compelling credo and an...