Here are a few articles that nicely illustrate how difficult it is to categorize people simply by their religion. Culture influences religion greatly. This is one reason why I often point out that many Mulisms do not live in the Middle East and are not Arab. Culture also has a large impact on the LDS Church.
African Muslims commemorate Magal
Did the Taliban understand Islam?
Cultural influence on religion in the US
The Rage Diaries on culture and religion