If the person says no, we might ask whether something in particular has caused him to doubt that God exists.
وَإِذَا رَدَّ بِٱلنَّفْيِ ،‏ فَبِإِمْكَانِنَا أَنْ نَسْأَلَهُ مَا إِذَا دَفَعَهُ أَمْرٌ مُعَيَّنٌ إِلَى ٱلشَّكِّ فِي وُجُودِ ٱللهِ .‏