Who Speaks for Islam? is written by John L. Esposito, founding
director of Georgetown University's Prince Alwaleed bin Talal Center
for Muslim-Christian Understanding, and Dalia Mogahed, executive
director of the Gallup Center for Muslim Studies.
The book is propaganda and the books (statistics) have been cooked. Read Robert Satloff's review in the Weekly Standard. It is "must reading" lest the trusting public be taken in because of Gallup's name and reputation.