Self-imposed Spiritual Blindness

وَقَالُوا۟ قُلُوبُنَا غُلْفٌۢ ۚ بَل لَّعَنَهُمُ ٱللَّهُ بِكُفْرِهِمْ فَقَلِيلًا مَّا يُؤْمِنُونَ

And they said, "Our hearts are wrapped." But, [in fact], Allāh has cursed them for their disbelief, so little is it that they believe.