One of the important moral issues dating back to ancient Greece is whether moral knowledge is independent of God's command or dependent upon it. The Mu'tazilites and Imāmiyya believe that reason is able to understand many moral values and that moral knowledge is intellectual and independent from God; therefore, it is superior to religion and even proving the existence of God and popular prophecy are feasible only by perceiving some moral values through reason. By adopting a descriptive and analytical approach through rereading and scrutinizing the moral verses of the Koran, this study seeks to answer the following question: what is the function of moral propositions of the Koran given the understanding of these propositions through reason? The results shows that the main purpose of the Holy Koran is moral education, acceptance and reference to previous moral knowledge of human being not imparting erudition. Various pieces of evidence can be presented on this claim, including keeping one's promise, gratefulness, following prototypes in moral advice and using the language of sermons instead of lecture and argument.