This essay is an attempt to understand the significance of Barth’s redefinition of the “law/gospel” rubric for political theology. Barth’s thought is exposited at length, and illumined by comparison with Luther and Calvin. Luther emphasizes the distance between gospel and the law, distinguishing between serving God in the secular regiment, and serving Christ in the spiritual regiment. He thereby challenges the improper relation of state and church, but does so in a manner that can lead to a passive dualism. Calvin holds that preaching the law to the state includes preaching the gospel; thus, the church has a positive vision against which it can evaluate the state’s service to God in Christ. This leads, however, to the danger of a ‘clerical guardianship’ of the state. Barth finds a positive connection between the two governments in the fact that both communities are based in Christ, in whom the gospel is their law. This grounds his high view of the state as predecessor to the heavenly kingdom, as well as a prophetic mission of the church to the state. This does not lead to a new Christendom, however, first, because Barth hopes not for a kingdom wrought by human hands, but for the Theocracy of God, and second, because Barth sees the fallen reality of both church and state, the state pagan and violent, and the church a poor witness. In the end, though Barth makes a strong case for supporting theological critique of the state, while avoiding Constantinianism, he is unable to solve the problem of how to connect the gospel and the law in the civil community.