Every attribute of God must be infinite as himself. He cannot be sometimes merciful, but not always merciful. He cannot be just, but not always just. Mercy belongs to him, and needs no contrivance of theologic chicanery to justify it.
“Then do you mean it is wrong to punish sin, and therefore God does not punish sin?”
By no means.
God does punish sin, but there is no opposition between punishment and forgiveness. The one may be essential to the possibility of the other. We are back to my question: Why does God punish sin?
“Because in itself sin deserves punishment,” do you answer?
Then how can God tell us to forgive it?
“He punishes, and having punished he forgives.”
That will hardly do. For if sin demands punishment, if the making right for sin is punishment, and righteous punishment is given, then the man is out from under sin’s claim upon him; he is free. Why should he now be forgiven?
“He needs forgiveness, because no amount of punishment can make up for the sin that is in his nature. Nothing will fully give him all he deserves.”
Then why not forgive him at once, if the punishment is not essential, if it does not adequately remedy the whole of the problem of sin? And this points out the fault in the whole idea.
— George MacDonald, Unspoken Sermons, Third Series, “Justice,” quoted in Discovering the Character of God, compiled by Michael Phillips, p. 257-258