Al-Quran—the Book of Guidance

Taqwa needed to comprehend it

While Quran is the Book of Guidance without a shade of doubt, ‘Taqwa’ the fear of Allah (SwT) needs to be imbibed in order to comprehend the divine message that Quran holds:

This is the Book; it is guidance sure, without doubt, to those who fear Allah’’ (2:2)

 Taqwa, whether it is the verb or noun connected to the root signifies the fear of Allah (SwT) the fear does not have by any negative connotation by any stretch of imagination. The fear has a positive outfall, as it acts as a restraining influence on falling into acts which are evil and immoral. The fear has a positive role in restraining ones tongue, the hand and the heart from evil. Once the restraining influence takes effect, righteousness followspiety and good conduct as well. 

On another count, in the Old Testament, according to writer of proverbs (i. 7) the fear of Allah (SwT) is the beginning of wisdom or we could as well say that wisdom dawns with fear of Allah. The wisdom takes us on to the path of Taqwa, wherein we comprehend the message that Al-Quran holds.  

It is further expounded in another Holy Verse:

But to those who receive Guidance, He increases the (light of) Guidance, and bestows on them their Piety and Restraint (from evil). (47:17) 

 The Holy Verse implies that the ones showing an active inclination to receive Guidance are in for reward, which Allah (SwT) provides by increasing the light of Guidance, and they are bestowed with special favours---restraint from evil and investing in piety. 

Restraint from evil and investing in piety leads to spiritual advancement, which is progressive, wherein each step makes the next one easier, as well as more complete from the previous one.