I don't recall anyone fire-bombing the British Embassy in Rome when the Life of Brian was released. The whole movie was about a mistaken belief that some guy called Brian was infact Our Lord and Saviour.
They had a go at the 3 Wise men creeping around the cow-shed a 2 o'clock in the morning -- The Saviour shacking up with some Welsh tart -- Crusifiction - one cross each, lying on the left -- the Saviour telling everyone to Fuck Off after he brought forth juniper berries.
No one cared. They just laughed it off.
If Islam is based on such solid beliefs then surely it can survive a little cartoon. If not then it must be one screwed up belief structure.