( ذلك بأنهم آمنوا ) أقروا باللسان إذا رأوا المؤمنين ، ( ثم كفروا ) إذا خلوا إلى المشركين ، ( فطبع على قلوبهم ) بالكفر ، ( فهم لا يفقهون ) الإيمان .
That is because they hypocritically professed faith, but faith did not reach their hearts, and then they secretly rejected Allah, so He put a seal on their hearts on account of their disbelief so that faith cannot enter it. Due to this seal they do not understand that in which lies their rectitude and righteousness.