i dont understand what's so complicated about it, if you insult someone's religion they get angry. If that person is poor, uneducated, disenfranchized, unemployed, and itching for someone to blame, their reaction will probably not be pleasant.
another thing is that religion is very much open to interpretation, so while u have muslim scholars condemning the attacks, u have extremists on the right saying its perfectly acceptable and encouraging it. Both claim to be muslim, but very different responses. THe same is true for Chrsitans who are'nt very christ like, but purport to be christian.