Book excerpt: What are the roots of today's militant fundamentalism in the Muslim world? In this insightful and wide-ranging history, Charles Allen finds an answer in an eighteenth-century reform movement of Muhammed ibn Abd al-Wahhab and his followers-the Wahhabi-who sought the restoration of Islamic purity and declared violent jihad on all who opposed them. The Wahhabi teaching spread rapidly-first throughout the Arabian Peninsula, then to the Indian subcontinent, where a more militant expression of Wahhabism flourished. The ranks of today's Taliban and al-Qaeda are filled with young men trained in Wahhabi theology. God's Terrorists sheds much-needed light on the origins of modern terrorism and shows how this dangerous ideology lives on today.