Jesus' identity as himself being God is also central to penal substitution. Those who do not believe that Jesus was God visiting the Earth in human form necessarily conclude that God chose a bystander named Jesus to suffer for others. However, those who believe that Jesus was actually God (; ) conclude that God—against whom mankind had sinned—came to accept the penalty upon himself. Thus, they see no injustice in God's choosing to come to Earth in order to take humanity's sin upon himself. However, the replies in these two paragraphs do not directly answer the objection that guilt is inherently non-transferable, whether the victim seeks to have it transferred or not. While they show that Jesus was not in the position of being punished involuntarily, they do not show that it is possible or just to punish a willing innocent victim in place of the guilty. J. I. Packer admits that proponents do not know how this could be possible but choose to believe it anyway.