It is ordained that non-believers are obstinate to the point of belief staying beyond their comprehension, even if miracles were to happen or angels were send down to them:
‘’They swear by God, with their utmost oaths, that if miracles were to come to them, they would believe in it. Say, the miracles were only with God. But, how do you know? Even if it did come, they still would not believe.’’ (06: 109)
It is recorded that Prophet Mohammad (PBUH) stated that Quran is the miracle. The sublimity of its message, the rhythm of its idiom, the appeal that it holds is indeed a miracle. Yet, the non-believers would not believe in the miracle of Quran, insisting on the physical exhibit of a miracle. Miracles stay in Divine Realm and Command. However, even with the physical exhibit of a miracle, the non-believers would not believe.
The non-believers failed to appreciate the truth from the very start, instead of reflecting on it and appreciating its veracity. The virtual rebellion against Divine Norms had the Almighty Allah turn their hearts and the vision:
‘’And We turn their hearts and their visions, as they refused to believe in it the first time, and We leave them blundering in their rebellion’’ (06: 110)
It was the rebellious nature of non-believers that led them to lose their visionary perception; it had a multiplier effect on the blunders they committed, one after another, leading them to abyss, where even the angels would not be enough to make them believe:
‘’Even if We send down the angels to them, and the dead spoke to them, and We gathered all things before them, they still would not believe, unless God wills; but most of them are ignorant’’ (06: 111)
Dead do not speak, but even if they were made to do so by Divine Will, and even if all evidence to support the truth was displayed, the non-believers still would not believe, unless God Wills. But in the Divine Premise, it is the willing believers who are taken on board, not the ignorant lot with their doubts and idiosyncrasies.