Allah says;
وَلَوْ أَنَّنَا نَزَّلْنَا إِلَيْهِمُ الْمَليِكَةَ
And even if We had sent down unto them angels,
Allah says;`Had We accepted what the disbelievers asked for,' that is -- those who swore their strongest oaths by Allah that if a miracle came to them they would believe in it -- `had We sent down angels,' to convey to them Allah's Message, in order to support the truth of the Messengers, as they asked, when they said,
أَوْ تَأْتِيَ بِاللّهِ وَالْمَليِكَةِ قَبِيلً
(or you bring Allah and the angels before (us) face to face). (17;92)
قَالُواْ لَن نُّوْمِنَ حَتَّى نُوْتَى مِثْلَ مَأ أُوتِىَ رُسُلُ اللَّهِ
They said;"We shall not believe until we receive the like of that which the Messengers of Allah had received." (6;124)
and,
وَقَالَ الَّذِينَ لَا يَرْجُونَ لِقَأءَنَا لَوْلَا أُنزِلَ عَلَيْنَا الْمَلَـيِكَةُ أَوْ نَرَى رَبَّنَا لَقَدِ اسْتَكْبَرُواْ فِى أَنفُسِهِمْ وَعَتَوْا عُتُوّاً كَبِيراً
And those who expect not a meeting with Us said;"Why are not the angels sent down to us, or why do we not see our Lord!" Indeed they think too highly of themselves, and are scornful with great pride. (25;21)
Allah said,
وَكَلَّمَهُمُ الْمَوْتَى
and the dead had spoken unto them,
This is, to inform them of the truth of what the Messengers brought them;
وَحَشَرْنَا عَلَيْهِمْ كُلَّ شَيْءٍ قُبُلً
and We had gathered together all things before them,
Ali bin Abi Talhah and Al-Awfi reported from Ibn Abbas,
before their eyes.
This is the view of Qatadah and Abdur-Rahman bin Zayd bin Aslam.
This Ayah means, if all nations were gathered before them, one after the other, and each one testifies to the truth of what the Messengers came with,
مَّا كَانُواْ لِيُوْمِنُواْ إِلاَّ أَن يَشَاء اللّهُ
they would not have believed, unless Allah willed,
for guidance is with Allah not with them. Certainly, Allah guides whom He wills and misguides whom He wills, and He does what He wills,
لَاا يُسْأَلُ عَمَّا يَفْعَلُ وَهُمْ يُسْأَلُونَ
(He cannot be questioned about what He does, while they will be questioned). (21;23)
This is due to His knowledge, wisdom, power, supreme authority and irresistibility.
Similarly, Allah said,
إِنَّ الَّذِينَ حَقَّتْ عَلَيْهِمْ كَلِمَةُ رَبِّكَ لَا يُوْمِنُونَ
وَلَوْ جَأءَتْهُمْ كُلُّ ءايَةٍ حَتَّى يَرَوُاْ الْعَذَابَ الاٌّلِيمَ
Truly, those, against whom the Word (wrath) of your Lord has been justified, will not believe. Even if every sign should come to them, until they see the painful torment. (10;96-97)
وَلَـكِنَّ أَكْثَرَهُمْ يَجْهَلُونَ
but most of them behave ignorantly