"And they say, 'Is it when we have disappeared into the earth?'" meaning: when we have become remains and dust. "Are we indeed to be in a new creation?" This is an interrogative form expressing denial; meaning: we will not be resurrected after death.
﴿وَقَالُوا أَئِذَا ضَلَلْنَا فِي الأَرْضِ﴾ أَيْ: إِذَا كُنَّا رُفَاتًا وَتُرَابًا ﴿أئنا لفي خلق جَدِيد﴾ وَهَذَا اسْتِفْهَامٌ عَلَى إِنْكَارٍ؛ أَيْ: إِنَّا لَا نُبْعَثُ بَعْدَ الْمَوْتِ
