mr. kalim, aurangzeb irrespective of whether one is upper caste or lower caste, he put hefty jajiya (the tax you have to pay , if u want to follow religion other than islam). And that way, got many poors converted to islam. forcibly converting them was his one man agenda. also, can u deny that practically even in islam, (irrespective of what u say) there are so many categories and one higher category/caste muslim will not marry lower caste muslim. So many muslim castes are there in the reservation list of govt, if u proclaim that there is no caste then even after hindreds and thousand of years of conversion, why your division of caste among yourself is there in islam. for proof, you just need to look at a matrimonial column in islamic section, which islamic caste bride/groom wants to marry outside of her/his caste. atleast hindus are more liberal *today* in terms of interactions and accepting fallibility of their old caste system , are open to debates, and mixing with greater vigour. but in islam , you stick to the dogma ; never tolerate the criticism that some age old belief need to be discarded now.
