There are two parts of the divine religion. One part of it may be called realization, and the other part obedience to commands. Although, both are equally important, just as soul and body are equally important for the human personality, there is a difference between realization and obedience to commands. That is, realization is central to the faith, unlike obedience of commands which is the relative part of the faith.
These two parts of religion have been mentioned in this hadith in which the Prophet Muhammad said: “Each verse of the Quran has an outer portion and an inner portion.” (Sahih ibn Hibban, Hadith No. 75).
In other words, one aspect of the verse of the Quran is in its lines and its second aspect lies between the lines. In the light of this hadith, the realization of faith is the name of the realization of religion while the commands of religion denote its external structure.
Let us examine the legal aspect of faith, which entails the recitation of these words: “There is no god but God and the Prophet Muhammad is the messenger of God.” One who utters these words has, according to religious law, become a believer but as far as the realization of
faith is concerned, it does not depend just upon the recitation of such words. The realized faith can be achieved only through an intellectual revolution, and not just by mouthing some words.
Source: Discovering God