Persistent disbelief and denial (kufr)

وَلَا يَزَالُ ٱلَّذِينَ كَفَرُوا۟ فِى مِرْيَةٍ مِّنْهُ حَتَّىٰ تَأْتِيَهُمُ ٱلسَّاعَةُ بَغْتَةً أَوْ يَأْتِيَهُمْ عَذَابُ يَوْمٍ عَقِيمٍ

But those who disbelieve will not cease to be in doubt of it until the Hour comes upon them unexpectedly or there comes to them the punishment of a barren Day.