[If a man recites the Qur’an and is not affected by it]

Answer: That does not indicate weakness or deficiency of the man’s faith. What indicates the deficiency and weakness of faith in a man is that he leaves some obligations, or commits some acts of disobedience; for that indicates the weakness and deficiency of his faith, even if he shows humility in reciting the Qur’an and weeps when hearing it!! For that does not benefit him, nor increase his faith.
- As for the one whom fear of Allah restrains from committing sins and from leaving obligations, then he is a believer, even if he is not affected by reciting the Qur’an and does not show humility when hearing it. However, the believer who is affected by reciting the Qur’an and shows humility when hearing it, together with his adherence to the God-consciousness of Allah, exalted is He, in fulfilling the obligations and leaving sins, is higher in rank and more complete in faith.
If it is said: Allah, exalted is He, has said: "The believers are only those who, when Allah is mentioned, their hearts become fearful, and when His verses are recited to them, it increases them in faith, and upon their Lord they rely" [al-Anfal:2], which indicates that the trembling of the hearts at the remembrance of Allah is among the necessary concomitants of faith.
Then it is said in reply: the meaning of His saying, exalted is He, "when Allah is mentioned, their hearts become fearful" is that when the believer is reminded of Allah as he is about to commit a sin, his heart trembles and he fears Allah, and he leaves the sin; and when he is reminded of Allah while he is heedless of performing an obligation, he fears Allah, exalted is He, and his heart trembles, and he turns to performing the obligation. This is the intended meaning of His saying, exalted is He: "when Allah is mentioned, their hearts become fearful."
And the meaning of His saying, exalted is He, "and when His verses are recited to them, it increases them in faith" is that when the verses of the Qur’an are recited to the believers, they affirm them and believe in them, and do not deny them as the disbelievers and hypocrites do. Every time the believer hears a verse from the Qur’an, he believes in it, and so his faith increases; and in this way his faith increases when he hears every verse and believes in it.
As for the disbeliever or the hypocrite, his disbelief increases when he hears each verse and disbelieves in it; and thus the disbelief of the hypocrite or the disbeliever increases when he hears every verse, because he disbelieves in everything he hears from the verses of the Qur’an.
And the explanation of His saying, exalted is He, "and upon their Lord they rely" is that the believers turn to Allah, exalted is He, alone in seeking success in their religious and worldly affairs, and they depend upon Him alone.

Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.3