During the time of Prophet Muhammad in Madinah, Muslims' understanding of the Concept of the other was strictly similar to the one described in the Holy Quranic verses. The Prophet himself provides an exemplary practice of the Islamic view of the Other in writing a constitution for people of different religions, tribes, races and ethnicities, living in Madinah. Those others who had agreed to that constitution were allowed to worship in their own way and follow their own religious law, and were given a degree of self-government. However, After Prophet Muhammad, Muslims' conceptions of the other greatly changed partly because of political reasons and conflicts among themselves and in most cases, because of the western colonization of many Muslim countries. The purpose of this paper is to deal with the diverging concepts of the other in Islam. It makes close readings of some Quranic verses revealed in the holy cities of Makka and Madinah and finds that the theoretical concept of the other, as represented in the Quran is based upon positive difference among peoples and communities. Then the paper sheds light on two instances of how Prophet Muhammad positively applied this concept, namely, "The Last Sermon and the Madinah Charter." Next, it surveys the manifestations of the concept of otherness in contemporary theory and practice, especially with reference to colonialism. The last section of this paper tries to interpret the radical changes that have turned the Muslim concept of the other from a positive one to a completely negative view of the other. Muslim contemporary othering is a comprehensive process that is divided by the researchers into exterior othering related to non-Muslims and domestic othering related to Muslims among themselves.