Allah tells us that the Qur'an is so eloquent and perfect in its wording and meanings, yet despite that the idolators do not believe in it. He tells us that their disbelief is the disbelief of stubbornness, as He says elsewhere:

وَلَوْ نَزَّلْنَـهُ عَلَى بَعْضِ الاٌّعْجَمِينَ

فَقَرَأَهُ عَلَيْهِم مَّا كَانُوا بِهِ مُؤْمِنِينَ

(And if We had revealed it unto any of the non-Arabs, and he had recited it unto them, they would not have believed in it.) (26:198-199). If the Qur'an had been revealed in the language of the non-Arabs, they would have said, because of their stubbornness:

لَوْلاَ فُصِّلَتْ ءَايَـتُهُ ءَاعْجَمِىٌّ وَعَرَبِىٌّ

(Why are not its verses explained in detail What! not in Arabic and an Arab) meaning, why is it not revealed in detail in Arabic And by way of denunciation they would have said, "What! not in Arabic nor from an Arab -- i.e., how can foreign words be revealed to an Arab who does not understand them This interpretation was reported from Ibn `Abbas, Mujahid, `Ikrimah, Sa`id bin Jubayr, As-Suddi and others.

قُلْ هُوَ لِلَّذِينَ ءَامَنُواْ هُدًى وَشِفَآءٌ

(Say: "It is for those who believe, a guide and a cure...") means, `say, O Muhammad: this Qur'an, for the one who believes in it, is guidance for his heart and a cure for the doubts and confusion that exists in people's hearts.'

وَالَّذِينَ لاَ يُؤْمِنُونَ فِى ءَاذَانِهِمْ وَقْرٌ

(And as for those who disbelieve, there is heaviness in their ears,) means, they do not understand what is in it.

وَهُوَ عَلَيْهِمْ عَمًى

(and it is blindness for them.) means they are not guided to the explanations contained therein. This is like the Ayah:

وَنُنَزِّلُ مِنَ الْقُرْءَانِ مَا هُوَ شِفَآءٌ وَرَحْمَةٌ لِّلْمُؤْمِنِينَ وَلاَ يَزِيدُ الظَّـلِمِينَ إَلاَّ خَسَارًا

(And We send down of the Qur'an that which is a healing and a mercy to those who believe, and it increases the wrongdoers nothing but loss.) (17:82).

أُوْلَـئِكَ يُنَادَوْنَ مِن مَّكَانٍ بَعِيدٍ

(They are called from a place far away.) Mujahid said, "Far away from their hearts." Ibn Jarir said, "It is as if the one who is addressing them is calling to them from a distant place, and they cannot understand what he is saying." This is like the Ayah:

وَمَثَلُ الَّذِينَ كَفَرُواْ كَمَثَلِ الَّذِى يَنْعِقُ بِمَا لاَ يَسْمَعُ إِلاَّ دُعَآءً وَنِدَآءً صُمٌّ بُكْمٌ عُمْىٌ فَهُمْ لاَ يَعْقِلُونَ

(And the example of those who disbelieve is as that of him who shouts to those (flock of sheep) that hears nothing but calls and cries. (They are) deaf, dumb and blind. So they do not understand.) (2:171)

Taking Musa as an Example

وَلَقَدْ ءَاتَيْنَا مُوسَى الْكِتَـبَ فَاخْتُلِفَ فِيهِ

(And indeed We gave Musa the Scripture, but dispute arose therein.) means, they disbelieved in him and did not show him any respect.

فَاصْبِرْ كَمَا صَبَرَ أُوْلُواْ الْعَزْمِ مِنَ الرُّسُلِ

(Therefore be patient as did the Messengers of strong will) (46:35).

وَلَوْلاَ كَلِمَةٌ سَبَقَتْ مِن رَّبِّكَ إِلَى أَجَلٍ مُّسَمًّى

(And had it not been for a Word that went forth before from your Lord,) i.e., to delay the Reckoning until the Day of Resurrection,

لَّقُضِىَ بِيْنَهُمْ

(the matter would have been settled between them.) means, the punishment would have been hastened for them. But they have an appointed time, beyond which they will find no escape.

وَإِنَّهُمْ لَفِى شَكٍّ مِّنْهُ مُرِيبٍ

(But truly, they are in grave doubt thereto.) means, their words of disbelief are not due to any wisdom or insight on their part; rather they spoke without any attempt at examining it thoroughly. This was also the interpretation of Ibn Jarir, and it is a plausible interpretation. And Allah knows best.