This conception of justice has dramatic implications for our view of the atonement. Can eternal punishment satisfy God’s justice? How is God’s anger “righteous” if, as the OT authors believed, it is His righteousness that impels Him to save? Beck says that for MacDonald, “Punishment alone doesn’t bring either ‘justice’ or ‘salvation.’ Punishment is only ever a tool toward these ends.”
This sermon hosts one of MacDonald’s — or anyone‘s — most eloquent missives against penal substitution theory:

The device [of substitutionary atonement] is an absurdity—a grotesquely deformed absurdity. To represent the living God as a party to such a style of action, is to veil with a mask of cruelty and hypocrisy the face whose glory can be seen only in the face of Jesus; to put a tirade of vulgar Roman legality into the mouth of the Lord God merciful and gracious, who will by no means clear the guilty. Rather than believe such ugly folly of him whose very name is enough to make those that know him heave the breath of the hart panting for the waterbrooks; rather than think of him what in a man would make me avoid him at the risk of my life, I would say, ‘There is no God; let us neither eat nor drink, that we may die! For lo, this is not our God! This is not he for whom we have waited!’