Allah O Akbar begins the call to prayer that resonates around minarets in towns and villages from Sinkiang to Morocco, from Paris to Timbuktu. Wherever in the world you are, the message is the same: 'God is Great.' It is also, however, the cry of fundamentalists throughout the lands of the faithful. Abbas, a member of the prestigious photo agency Magnum, has spent seven years travelling through the Islamic world to capture the diverse and striking...