Above all, had God done nothing about the sin committed in Eden, his own trustworthiness would have been called into question.
وَٱلْأَهَمُّ أَنَّ ٱلْمَلَائِكَةَ وَٱلْبَشَرَ كَانُوا سَيُشَكِّكُونَ فِي مِصْدَاقِيَّتِهِ .‏