Also unto thee, O Lord, belongeth mercy; for thou renderest to every man according to his work.
— Psalm 62 v.12

If it be said by any that God does a thing which seems to me unjust, then either I do not know what the thing is, or God does not do it. If, for instance, it be said that God visits the sins of the fathers on the children, a man who takes visits upon to mean punishes, and the children to mean the innocent children, ought to say, “Either I do not understand the statement, or the thing is not true, whoever says it.” God may do what seems to a man not right, but it must so seem to him because God works on higher, divine, perfect principles too right for a selfish, unfair, or unloving man to understand. But least of all must we accept some low notion of justice in a man, and argue that God is just in doing after that notion.

The common idea, then, is that the justice of God consists in punishing sin: it is in the hope of giving a larger idea of the justice of God in punishing sin that I ask, “Why is God bound to punish sin?”  If a man say, “How could a just God not punish sin?” I answer that mercy is a good and right thing, and but for sin there could be no mercy. We are told to forgive, to be as our father in heaven. Two rights cannot possibly be opposed to each other. If God punish sin, it must be merciful to punish sin; and if God forgive sin, it must be just to forgive sin. He cannot be sometimes merciful, and not always merciful. He cannot be just, and not always just. Mercy belongs to him, and needs no contrivance of theological trickery to justify it.