ذَٰلِكَ بِأَنَّهُمْ آمَنُوا ثُمَّ كَفَرُوا فَطُبِعَ عَلَىٰ قُلُوبِهِمْ فَهُمْ لَا يَفْقَهُونَ
Thalika bi-annahum amanoo thumma kafaroo fatubiAAa AAala quloobihim fahum la yafqahoona
That (is) because they believed, then they disbelieved; so were sealed [upon] their hearts, so they (do) not understand.
this, because [they profess that] they have attained to faith, whereas [inwardly] they deny the truth - and so, a seal has been set on their hearts so that they can no longer understand [what is true and what false].
That is because they believed, then they rejected Faith: So a seal was set on their hearts: therefore they understand not.
That is because they believed, then disbelieved, therefore their hearts are sealed so that they understand not.
That is because they believed, then disbelieved; thus their hearts are sealed, so they understand not.
That is because they believed, and then they disbelieved; so their hearts were sealed over, and they do not understand.