Under what authority can you decide bin Laden or Sadam Hussein are not true followers of Islam? Bin Laden would say he IS a true follower, each of the hijackers would say that he was a true follower. The hate spewing mullahs would claim they too are true followers. There is no Vatican or Pope or ultimate authority in Islam and you aren't it either.
Do you also insult Jews and Protestants because they don't have this "authority"?