The Mu’tazilah makes up the "extrovert dimension" of Islamic culture. In this article three aspects of extrovert dimensions will be examined. First of all, as Islam expanded geographically, it met many cultural challenges which created lively debates between Muslims and alien cultures, beliefs and philosophies. In this process, the Mu’tazilah came forward to defend Islamic belief against its opponents. Particularly during the Abbasid period the intellectual challenges were met successfully by the Mu’tazilite theologians. Secondly, these religious and philosophical challenges and counter challenges forced all parts to translate ancient literatures, such as Greek, Indian, Persian ones in order to enhance their arguments. Thirdly, these translated literatures prepared a solid ground in the Islamic culture so that Islamic philosophy and natural sciences to be flourished. The Mu’tezilite theology which was much more related to those literatures became a theological philosophy rather than simply a theology. During the Classical period, the Mu’tazilah became ardent defenders and supporters of natural sciences in all Muslim lands.