In November 2007, in the Gaza Strip town of Khan Younis, I watched and filmed as a group of black-clad fighters concluded their afternoon prayers, their Kalashnikov semi-automatic rifles piled alongside. "Our prayer helps us to face fears and to face death and to give meaning and to be the idol that other people look for," said a young man called Mohamed Abu Muailek.

He went inside a room to search Google Earth for a target to strike across the Israeli border. "Our rockets will be aimed there," he said in excellent English,...