When in Rome .... Like you, I too was very surprised. Call it the Pope Francis mystique. When he speaks, he uses simple and direct words. From all that I have read, this is what attracts so many to him. As to the Imam's sincerity, he was so moved at the actions taken by Pope Francis in holding a worldwide vigil service for peace in his country, that he flew to Rome in order to attend. Perhaps he can be a catalyst in his own country to call for a similar prayer vigil by Muslims. Never doubt the power of prayer! Never!
Do you not think the Muslims prayed to their "god" before the Battle of Lepanto? Do you know which side won in that battle?