What does Karl Barth say about the wrath of God? The phrase "wrath of God" appears a handful of times in the bible, and perhaps the most famous occurrence is in Romans 1:18: "For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who hold the truth imprisoned in the chains of their unrighteousness." In Karl Barth's famous commentary on Romans, his initial reaction to Romans 1:18 was "In the name of God! We know not what we should say to this."

Karl Barth begins his commentary on the "wrath of God" (Rom 1:18), by saying that God is wholly other, and unknown to us. God is unknown to us naturally, there is nothing like God, and nothing in creation that is an analogy of being (analogia entis) to God. Barth invokes Job and Martin Luther to describe God as the "hidden God" (deus absconditus) that we may only fear. God is hidden to us, until God is self-manifested to us, and God's self-revelation is the righteousness of God. The revelation of the righteousness of God, is wrath to all sinful creaturely opposition. So the wrath of God, occurs when the righteousness of God is opposed. God speaks (deus dixit), and God say No! to everything that has said no to God. The wrath of God is God's speaking No! to all no's that reveals a hidden Yes! to us all. 

On Romans 1:18, Karl Barth writes, "In the name of God! We know not what we should say to this. The believer knows our ignorance. With Job, he loves the God who in His unsearchable eminence is only to be feared: with Luther, he loves the deus absconditus ['the hidden god']. To him is manifested the righteousness of God. He shall be saved, and he alone. Only the prisoner shall be free, only the poor shall be rich, only the weak strong, only the humble exalted, only the empty filled, only nothing shall be something' (Luther). But against the ungodliness and unrighteousness of men there is revealed the wrath of God." [1]

Karl Barth does not envision the "wrath of God" along the fundamentalist lines of eternal conscious torment or an armageddon, or as the self-correcting nature of the world, etc. Barth describes the wrath of God as God's self-revelation, and the righteousness of God results in the liberation of the world self-imprisoned in ungodliness and unrighteousness due to the sin of humanity. The wrath of God is therefore the release of the world from its chains, adding what is lacking, and removing what is excess, such that all things conform to the righteousness of God. The revelation of Jesus Christ is the specific event of God's self-manifestation, who through him we know the righteousness of God and the wrath of God, as they are both revealed in Jesus.

The following is Barth's commentary on "the wrath of God" (Rom 1:18) from his Epistle to the Romans, which I've summarized above. Barth speaks primarily of the wrath of God and the righteousness of God in the event of the self-revelation of God. Barth speaks here in general terms, but does not fully address the doctrine of reconciliation at this loci. I recommend reading the Church Dogmatics Vol. IV/1, The Doctrine of Reconciliation for a more complete explanation of how this relates specifically to Jesus (I recommend beginning with CD IV/1 §52.2 "Judge Judged in Our Place ).

The wrath of God is the judgement under which we stand in so far as we do not love the Judge; it is the' No' which meets us when we do not affirm it; it is the protest pronounced always and everywhere against the course of the world in so far as we do not accept the protest as our own; it is the questionableness of life in so far as we do not apprehend it; it is our boundedness and corruptibility in so far as we do not acknowledge their necessity.

The judgement under which we stand is a fact, quite apart from our attitude to it. Indeed, it is the fact most characteristic of our life. Whether it enters within the light of salvation and of the coming world depends upon the answer we give to the problem of faith. But it is a fact, even should we choose the scandal rather than faith (Rom 1:16). That time is nothing when measured by the standard of eternity, that all things are semblance when measured by their origin and by their end, that we are sinners, and that we must die—all these things ARE, even though the barrier be not for us the place of exit.

Life moves on its course in its vast uncertainty and we move with it, even though we do not see the great question-mark that is set against us. Men are lost, even though they know nothing of salvation. Then the barrier remains a barrier and does not become a place of exit. The prisoner remains a prisoner and does not become the watchman. Then is waiting not joyful but a bitter-sweet surrender to what is inevitable. Then is the contradiction not hope, but a sorrowful opposition. The fruitful paradox of our existence is then that which consumes it like a worm.

And Negation is then—what is normally meant by the word. In the place of the Holy God there then appear Fate, Matter, the Universe, Chance, ANANKE [The Greek primordial goddess of inevitability, compulsion, and necessity]. Indeed, a certain perception is betrayed when we begin to avoid giving the name 'God' to the 'No-God' of unbelief (Rom 1:17). That which we, apart from faith in the resurrection, name 'God', is also a final consequence of the divine wrath. But the God who, contradicting His own name, affirms the course of this world, is God—God in His wrath, God who sorrows on our behalf, God who can only turn Himself from us and say only 'No'. And yet, for this very reason, no upright man can unreservedly name Him 'God'. For the wrath of God cannot be His last word, the true revelation of Him! 'Not-God' cannot seriously be named 'God'.

Nevertheless, it is, in fact, always God against whom we are thrust. Even the unbeliever encounters God, but he does not penetrate through to the truth of God that is hidden from him, and so he is broken to pieces on God, as Pharaoh was (Rom 9:15-18). 'Everything that thwarts and damages the life that has been made by God, all the frailty and bondage of the creaturely life, including the sentence of death under which it lies, is a reaction of the power of God' (Zündel). Yes, but we must add that, if we do not make the apprehension of this divine reaction our own, we must perish at its hands. The whole world is the footprint of God; yes, but, in so far as we choose scandal rather than faith, the footprint in the vast riddle of the world is the footprint of His wrath. The wrath of God is to unbelief the discovery of His righteousness, for God is not mocked. The wrath of God is the righteousness of God—apart from and without Christ. [2]

Sources:

1. Barth, Karl. The Epistle to the Romans, trans. Edwyn C Hoskyns, Oxford University Press, 1980, p. 42 

2. Ibid. pp. 42-43