It is interesting to read about the newest survey of the world’s Muslim population conducted by the Pew Research Center in Washington, DC, according to which the second-biggest faith is not so Arabian (“A Shifting Locus,” October 10, 2009). As it turns out, some sixty percent of the total of more than a billion-and-a-half Muslims live in Asia and the Pacific basin, while only about thirty-five percent of them live in the Middle East and Africa. Similarly, it is worthy of note that the European country with the highest Muslim population is not France or Germany but Russia, where they represent nearly twelve percent of the total. However, it would also be useful to learn about the geographic distribution of different branches of Islam, such as Sunni, Shia, Kharijite, and Sufi. Just like Catholics, Protestants, and Orthodox Christians, Muslims of the world differ significantly in their world-views depending on the branch of their faith to which they belong. The geographic breakdown that you report neglects these important differences.