accountability for rejecting guidance

مِن قَبْلُ هُدًى لِّلنَّاسِ وَأَنزَلَ ٱلْفُرْقَانَ ۗ إِنَّ ٱلَّذِينَ كَفَرُوا۟ بِـَٔايَـٰتِ ٱللَّهِ لَهُمْ عَذَابٌ شَدِيدٌ ۗ وَٱللَّهُ عَزِيزٌ ذُو ٱنتِقَامٍ

Before, as guidance for the people. And He revealed the Criterion [i.e., the Qur’ān]. Indeed, those who disbelieve in the verses of Allāh will have a severe punishment, and Allāh is Exalted in Might, the Owner of Retribution.

أَفَلَا يَتَدَبَّرُونَ ٱلْقُرْءَانَ أَمْ عَلَىٰ قُلُوبٍ أَقْفَالُهَآ

Then do they not reflect upon the Qur’ān, or are there locks upon [their] hearts?

فَمَا لَهُمْ لَا يُؤْمِنُونَ

So what is [the matter] with them [that] they do not believe,