The Unending Feud: Shi'ites vs. Sunnis

There is no god but God, and Muhammad is the Messenger of God."

That confession of faith, the shahada, is professed by all Muslims, be they the 700 million Sunnis who dominate the Islamic world from Morocco to Indonesia or the 90 million Shi'ites who rule Iran and form majorities in Lebanon, Bahrain and Iraq. To the shahada, however, the Shi'ites add, "And Ali is the Friend of God." Those additional words in praise of Ali, whom the Shi'ites passionately claim is Muhammad's true successor, epitomize the complex and often bloody feud between Islam's two branches.

Among the close disciples of...