To the doctrine of substitution, it might be objected that:-
1. It is unnecessary, since God could forgive sinners without any additional condition or requirement. But God is not only perfect love, desiring the salvation of the sinner, but also perfect justice. The Puritans used to say that there are three things that even God cannot do: he cannot die, lie, or deny himself. And for God to simply turn a blind eye to sin would be for him to deny his own nature.
2. It is impossible, for guilt cannot be transferred from one person to another, neither can the penalty deserved by a guilty person be born by an innocent party. The innocent may suffer, but surely not as the punishment for the wrong-doing of another?
3. It is immoral for the innocent to suffer in place of the guilty. But it is not immoral when the innocent voluntarily pays the penalty, and shoulders the burden, Heb 10:7. Still less is it immoral when the innocent victim knows he has the ability to bring deliverance to many other, has the power to release himself from the punishment, Jn 10, foresees an ample and unparalleled reward, Heb 12:2; Php 2:8-11.