In order to save mankind from sin, the rescuer would have to provide a means of atonement, a way of reconciling humans to God by undoing the effects of sin.
وَمَاذَا كَانَ مُخْتَارُ يَهْوَه سَيُعَانِي عَلَى وَجْهِ ٱلتَّحْدِيدِ ؟‏