Allah says:

[فَلاَ يَحْزُنكَ قَوْلُهُمْ]

(So, let not their speech then grieve you.) means, `their denying you and their disbelief in Allah.'

[إِنَّا نَعْلَمُ مَا يُسِرُّونَ وَمَا يُعْلِنُونَ]

(Verily, We know what they conceal and what they reveal.) means, `We know everything about them, and We will punish them for their false claims and deal with them accordingly on the Day when none of their deeds, great or small, major or minor, will be overlooked, and every deed they did throughout their worldly lives will be laid open for examination.'

[أَوَلَمْ يَرَ الإِنسَـنُ أَنَّا خَلَقْنَـهُ مِن نُّطْفَةٍ فَإِذَا هُوَ خَصِيمٌ مٌّبِينٌ - وَضَرَبَ لَنَا مَثَلاً وَنَسِىَ خَلْقَهُ قَالَ مَن يُحىِ الْعِظَـمَ وَهِىَ رَمِيمٌ - قُلْ يُحْيِيهَا الَّذِى أَنشَأَهَآ أَوَّلَ مَرَّةٍ وَهُوَ بِكُلِّ خَلْقٍ عَلِيمٌ - الَّذِى جَعَلَ لَكُم مِّنَ الشَّجَرِ الاٌّخْضَرِ نَاراً فَإِذَآ أَنتُم مِّنْه تُوقِدُونَ ]

(77. Does not man see that We have created him from Nutfah. Yet behold he (stands forth) as an open opponent.) (78. And he puts forth for Us a parable, and forgets his own creation. He says: "Who will give life to these bones after they are rotten and have become dust'') (79. Say: "He will give life to them Who created them for the first time! And He is the All-Knower of every creation!'') (80. He Who produces for you fire out of the green tree, when behold you kindle therewith.)