"Allah O Akbar" begins the call to prayer that resonates from minarets in towns and villages from Sinkiang to Morocco, from Paris to Timbuktu. No matter where in the world you are, the message is the same: "God is great". It is also the war cry of Islamic militants throughout the lands of the faithful.

Abbas has traveled throughout the Islamic world for seven years to take the photographs for this book. Driven by a desire to understand and expose the internal tensions within Muslim societies, he highlights the conflict between a rising political movement looking for inspiration in a mythical...