There are three methods of religious thought in Islam. The Holy Quran in its teachings points to three paths for Muslims to follow in order to comprehend the purposes of religion and the Islamic sciences: (1) the path of the external and formal aspect of religion (the Shari‛ah); (2) the path of intellectual understanding; and (3) the path of spiritual comprehension achieved thought sincerity (ikhlas) in obeying God.
It can be seen that the Holy Quran in its formal aspect addresses all people without providing any demonstration or proof. Rather, depending on the unique sovereignty of God, it commands people to accept the principles of faith such as divine unity, Prophet hood, eschatology; it gives them practical injunctions such as daily prayers, fasting, etc.; and at the same time it prohibits them from committing certain other actions. Yet if the Quran had not provided authority for these commands it would never have expected man to accept and obey them. It must, therefore, be said that such simple utterances of the Quran are a path toward the understanding of ultimate religious ends and the comprehension of the Islamic sciences. We call such verbal expressions as “Believe in God and His Prophet” and “Perform the prayers,” the external or formal aspect of religion.
In addition to guidance in the external aspect of religion, we see that the Holy Quran in many verses guides man toward intellectual understanding. It invites man to meditate, contemplate and deliberate upon the sign of God in the macrocosm and the microcosm. It explains many verities thought unfettered intellectual reasoning. It must be said in truth that no sacred book praises and recommends science and intellectual knowledge for man as much as does the Quran. In many of its words and utterances the Quran attests to the validity of intellectual proof and rational demonstration, that is, it does not claim that man should first accept the validity of the Islamic sciences and then through intellectual proofs justify these sciences. Rather, with complete confidence in the truth of its own position it proclaims that man should use his intellect to discover the truth of the Islamic sciences, and only then accept this truth. He should seek the affirmation of the words contained in the Islamic message in the world of creation which is itself a truthful witness. And finally man should fine the affirmation of his faith in the results of rational demonstration; he should not have to gain faith first and then, in obedience to it, seek proofs. Thus philosophical thought is also away whose validity and efficacy is confirmed by the Holy Quran.
Also, in addition to guidance in the external in intellectual aspects of religion, we see that the Holy Quran in subtle terms explains that all true religious science originates and comes from Divine Unity (tawhid) and the knowledge of God and His Attribbutes. The perfection of the knowledge of God belong to those whom He has drawn from all places and elevated solely to Himself. It is these men who have forgotten themselves and all things and as a result of sincerity in obedience to God have been able to concentrate all their power and energies upon the transcendent world. Their eyes have become illuminated through the vision of the light of the pure Creator. With the eye of discernment they have seen the reality of things in the kingdom of heaven and earth, for through sincerity of obedience they have reached the station of certainty (yaqin). As a result of this certainty the kingdoms of heaven and earth and the immortal life of the eternal world have become revealed to them.
Deliberation upon the following holy verses illuminates fully this claim: “And We sent no messenger before thee but We inspired him (saying): There is no God save Me (ALAH), so worship Me” (Quran, XXI,25); and, “Glorified be Allah from that which they attribute (unto Him), save signel-minded slaves of Allah” (Quran,XXXVII,159-160); and, “say, I am only a mortal like you. My Lord inspireth in me that your God is only one God. And whoever hopeth for the meeting with his Lord, let him do righteous work, and make none sharer of the worship due unto his Lord” (quran WVIII,111); and, “And server the Lord till the inevitable {al-yaqin} cometh unto thee” (quran.XV,99); and God says, “Thus did We show Abraham the kingdom of the heavens and the earth that he might be of those possessing certainty” (Quran, VI, 76); and “Nay, but the record of the righteous is in ‛IIiyin-Ah! What will convey unto thee what ‛IIiyin is! –A written record, attested by those who are brought near (unto their Lord)” (Quran, LXXXIII,18-21); and, “Nay, would that ye knew (now) with a sure knowledge {‛ilm al-yaqin}! Ye will behold hellfire” (Quran, XII, 5-6).
Thus it may be said that one of the path for the comprehension of religious verities and sciences is the purification of the carnal soul and sincerity in obedience to God.