Get rid of the idea that judgement is chiefly retribution, and directly infliction. Realise that it is, positively, the establishing and the securing of eternal righteousness and holiness. View punishment as an indirect and collateral necessity, like the surgical pains that make room for nature's curing power. You will then find nothing morally repulsive in the idea of judgment effected in and on Christ, any more than in the thought that the kingdom was set up for him.
God could only justify man before him by justifying himself and his holy law before men. If he had not vindicated his holiness to the uttermost in that way of judgment, it would not be a kind of holiness that men could trust. Thus a faith which could justify man, which could make a foundation for a new humanity, could not exist. We can only be eternally justified by faith in a God who justifies himself as so holy that he must set up his holiness in human history at any price, even at the price of his own beloved and eternal Son.
I close, then, upon that unchangeable word of God's self-justifying holiness. Even the sinner could not trust a love that could not justify itself as holy. It is the holiness of God's love, I urge, that alone enables us to trust him. Without that we should only love him, and the love would fluctuate. For we could not be perfectly sure that his would not. It is the holiness in God's love that is the eternal, stable, unchangeable element in it - the holiness secured for history and its destiny in the Cross. It is only the unchangeable that we could trust; and there alone we find it. If we only loved the love of God, we should have no staple, eternal, universal religion. But we love the holy love he established in Christ, and therefore we are safe with an everlasting salvation.
From P T Forsyth's The Work of Christ, pages 122-3