Under “The problem of Justification,” in Barth’s treatment of the doctrine in Church Dogmatics, he explains that although in studying justification, one is dealing more specifically with the positive aspect of God’s two-fold judgment and sentence, the negative aspect of God’s judgment and sentence belong together with the positive.
Therefore the positive sense of the sentence executed in that judgment belongs together with the negative. … And what we have to show is that this is possible, that the two belong together: our real sin and our real freedom from sin; our real death and our real life beyond death; the real wrath of God against us and His real grace and mercy towards us; the fulfillment of our real rejection and also of our real election. … the No of God behind the Yes of God before, but the Yes of God only before as the No of God is behind. This history, the existence of man in this transition, and therefore in this twofold form, is the judgment of God in its positive character as the justification of man. (CD, IV, §61: 516)