Do you know that even though all Muslims seem the same, but there are huge differences amongst them when you start rummaging through their societies, culture and laws. Yes, there are as many kinds of Muslims as you can imagine, even though most times we are lumped together with Osama bin Ladin and his ilk. There are differences in how in each society, each sub group perceive and practice their religious ideology (or dogma). Each sub-group shares some basic principals with the other groups but may be dramatically different their understanding of the shariah and fiqh for everything in life like woman's rights, purdah, performance arts, food, etc.
I think the main problem of the Muslim world stems from the fact that though we acknowledge the different interpretations of our religion but we do not tolerate the differences. The Wahabis (aka Salafi, Ahl e Hadis, Demobandi, Salafi) would not tolerate the Barelvis or the Shias. Qadianis (a renegade sect) and are pronounced non-Muslims in several Muslim countries (add ref.) and Ismali Shias are looked at with suspicion because of their devotion to Aga Khan. Sufis another group who are greatly admired for humanity and non violence, are declared non Muslims by several sects. Well, there are smaller groups of liberal/secular/progressive consisting of people from these difference sects, who want to rise above the tussles we have within the deen. And then, we also have those who are so tired of all of this or just are not religious but call themselves Muslims and keep the religion as their cultural and political identity. These groups would perhaps be considered non Muslim by literalists among us. Each sect thinks that they are right and sometimes feels free to declare some other group as Kharij or out of the religion.
I feel frustrated to see that we do not have a Ummah which would act like a body, so that when part is hurt the other parts can also feel it. Each of us is fighting to win the battle for supremacy of our own ideology. May be the Western world is right in ridiculing us!!!