Eberhard Jungel (Justification, 78-80) defines God’s righteousness in terms of His self-consistency: “the doctrine of justification sees God as being utterly consistent with himself and therefore righteous, when it conceives of him as the justifying God who justifies not the righteous, but the unrighteous, not the pious, but the ungodly.”
God is righteous, and so in proving righteous in the cross, He is proving Himself to be God. Christ is no contraction or contradiction of God’s divinity: “God’s humanity is the clearest expression of his divinity, not a contradiction of it.”
But how is this the case?
Jungel argues, “Justification is inconceivable without God taking on himself the results of human ungodliness and in that very way remaining God. Only in his identification with the crucified Jesus, made ungodly in his accursed death, is God’s righteousness so evident that human beings, though they make themselves ungodly, can become righteous (that is, people suitable for God). . . . In Jesus Christ crucified, God is consistent with, in concord with himself by the fact that he himself brings people who are in conflict with him into being in concord.”This formulation is fully consistent with classic Protestant soteriology, but is useful in highlighting the implications of justification for theology proper. Justification tells us something about God; it in fact displays and reveals His Godness precisely because it is a revelation of His righteousness, His utter self-consistency.
And this also highlights an important difference from pre-Reformation formulations of justification. As Jungel says elsewhere in his book, Augustine taught that “‘the righteousness of God’ is . . . ‘not . . . that whereby the Lord is righteous, but whereby He justifieth those whom of ungodly He maketh righteous.’ . . . one of the relative weaknesses in this basically accurate exposition is that it makes a separation between God’s action in making righteous and the fact that he is righteous. The doctrine of justification would then have no meaning for the concept of God” (75).