Abstract. The distinctive feature of al-Attas’s definition of God compared with Western’s definition is based on the Islamization process upon the Arabic language occurred during Quranic revelation. Al-Attas affirmed that Quranic revelation was a scientific-metaphysical work altering Arabic key meanings and crucial concepts through its semantic structure without shifting its literal form. Such a process was regarded later as an improved theological system constructing Islamic Worldview carrying out new concepts of God, truth, reality, science, etc. Rather than reconstructing its literal form, Quranic revelation developed fresh key meanings and crucial concepts embedded in Arabic Word and institutionalized it as a standard language of Islamic World further. This research found that al-Attas affirmed Islamic Revelation as a scientific-metaphysical process manifested in a transformation of the semantic meaning of Jahiliyya Arabic then standardized as the language used by major Muslim. This process also guaranteed several fundamental differences owned by Western Worldview regarding the definition of God and concepts exposed from it, including 'Theistic Science'.