The study of the Quran's comprehensiveness is one of modern studies concerning the Qur'anic sciences and interpretation. The Quran's comprehensiveness means that the Holy Qur'an covers all aspects of life, whether political, social, economic or others. On the other side, there is secularism that rejects this fact. Secularists have distorted the Qur'anic concepts and meanings and taken them away from their purposes, just to promote secularism in Muslim societies. After proving that the Qur'an covers all aspects of man's life, we have discussed in this article the views of secularism with criticism and analysis, refuting their claims that religion and the Holy Qur'an have had nothing to do with social and political rules. The secularistic view that denies any interference of religion in worldly matters is certainly false. It is not consistent with the universal teachings of the Qur'an concerning worldly affairs, and the effective role of those teachings in man's life and his seeking to gain happiness and perfection. The Holy Qur'an mentions the principles of social relations and general basics and rulings of political system, and this indicates its comprehensiveness of both social and political dimensions. On the other hand, the interpretation of the Qur'anic verses by secularists for proving the separation of religion from society, politics, and government, is either an interpretation by one's own opinion, or an interpretation without paying any attention to the rational and verbal indications or evidences.