Caste system is their in every religion, but in some other format. Why the hell Muslims bomb mosque and kill one another in Iraq and Pakistan, it is indeed a different type of caste system, the purest form of Vedas have no castes, they are all added later on its voyage form one century to another, since it's the oldest relegion of all. I am not here to argue whose religion is better, my point is why Islam preaches non believers to be either converted to Islam or killed, why it is not allowing a person to think or have his own opinion.