Lack of religious understanding (fiqh)

لَأَنتُمْ أَشَدُّ رَهْبَةً فِى صُدُورِهِم مِّنَ ٱللَّهِ ۚ ذَٰلِكَ بِأَنَّهُمْ قَوْمٌ لَّا يَفْقَهُونَ

You [believers] are more fearful within their breasts than Allāh. That is because they are a people who do not understand.