ذَٰلِكَ بِأَنَّهُمۡ ءَامَنُواْ ثُمَّ كَفَرُواْ فَطُبِعَ عَلَىٰ قُلُوبِهِمۡ فَهُمۡ لَا يَفۡقَهُونَ
That is because they declared faith (in Islam apparently), then disbelieved (secretly). Therefore a seal has been set on their hearts, and thus they do not understand
Author: Muhammad Taqi Usmani