Allah (swt) again emphasizes the affirmation by using (And indeed). Allah (swt) does not only know those who disbelieve openly; rather, He knows who hide it in their hearts. Those disbelievers, clearly disbelieved in Allah (swt) and the hereafter; otherwise, they would have believed in the Day of Judgement and followed the Way of Guidance which the Prophet (saws) has brought. Furthermore, they denied the prophecy of the Prophet (saws). Thus, this is a threat and warning from Allah (swt) to the deniers because they disbelieved the Holy Quran although it is miraculous.