3ذٰلِكَ بِأَنَّهُم آمَنوا ثُمَّ كَفَروا فَطُبِعَ عَلىٰ قُلوبِهِم فَهُم لا يَفقَهونَMuhammad Asadthis, because [they profess that] they have attained to faith, whereas1 [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].2The particle thumma ("and then") has often the same function as the simple conjunctive wa ("and"), which in this case may be properly rendered as "whereas".See surah 2, note 7.