Thirty-seven years ago, at the age of 32, Moustapha Dali quit show business. An Algeria native, he'd begun to build an acting career in France but tired of his Paris agents telling him he'd have to change his name to one "less Arabic, more French." As Dali recounts it, "I told them I wanted to keep my name. I said Omar Sharif didn't change his name, but they said, 'He's not a French actor, he works in Hollywood.' " Today, at age 69, the scholarly, erudite Dali is the soft-spoken but righteous rector of the Mosquee Al Madina, the main...