﴿ إِنَّمَا ٱلْمُؤْمِنُونَ ٱلَّذِينَ إِذَا ذُكِرَ ٱللَّهُ وَجِلَتْ قُلُوبُهُمْ وَإِذَا تُلِيَتْ عَلَيْهِمْ ءَايَٰتُهُۥ زَادَتْهُمْ إِيمَٰنًۭا وَعَلَىٰ رَبِّهِمْ يَتَوَكَّلُونَ ﴾

“Believers are only they whose hearts tremble with awe whenever God is mentioned, and whose faith is strengthened whenever His messages are conveyed unto them, and who in their Sustainer place their trust -”

The believers those whose faith is complete are only those who when God is mentioned that is when His threat of punishment is mentioned their hearts tremble fear and when His verses are recited to them they increase their faith their acceptance of the truth and who rely upon their Lord who put their trust in Him alone and not in any other.