‘[Jesus] is the unrighteous among those who can no longer be so because He was and is for them. He is the burdened amongst those who have been freed from their burden by Him. He is the condemned amongst those who are pardoned because the sentence which destroys them is directed against Him. He who is in the one person the electing God and the one elect man is as the rejecting God, the God who judges sin in the flesh, in His own person the one rejected man, the Lamb which bears the sin of the world that the world should no longer have to bear it or be able to bear it, that it should be radically and totally take away from it.
This is undoubtedly the mystery of divine mercy. God acted in this way because He grieved over His people, because He did not will to abandon the world to its unreconciled state and therefore on the way which leads to destruction, because He wiled to show it an unmerited faithfulness as the Creator, because in His own inconceivable way He loved it. But in this respect it is as well to be clear that the mystery of His mercy is also the mystery of His righteousness. He did not take the unreconciled state of the world lightly, but in all seriousness. He did not will to overcome and remove it from without, but from within. It was His concern to create order, to convert the world to Himself, and therefore genuinely to reconcile it. He did not, therefore, commit an arbitrary act of kindness – which would have been no help to the world. He did what we might call a neat and tidy job. He accepted the world in the state in which He found it, in its alienation from Himself, in the state of sinful men. To bring about this conversion He really took the place of man. And He did not take the place of this man as God but as man: “to fulfill all righteousness,” to do right at that very place where man had done wrong, and in that way to make peace with man, to the triumph of His faithfulness, to His own magnifying in creation and by the creature. The Word became flesh that there might be judgement of sin in the flesh and the resurrection of the flesh.’ (Karl Barth, ‘Church Dogmatics’, IV.1 p. 237)