More on the kingdom of God

Now it is a mistake, often committed by those who take this line in theology, to maintain that in the theory of the Two Realms—that is, in their distinction between the Gospel and the Law—the Reformers proclaimed that the world, and above all the State, is “autonomous”. This could only be the case if they did not declare the law of God to be binding on the State; Luther certainly never said this; at the most, the only people who might have said something of this kind would be neo-Lutheran romantics and nationalists. On the other hand, these “Christological” theologians would only be justified in their reproach, if they believed in a State which could be governed by the Gospel of Grace, and not by means of compulsory law—which would be pure fanaticism, or if they gave up saying that the real Kingdom of Christ is only achieved through the Word. For the State will never, never be governed by the Word—in the sense of the Gospel—but exclusively by the word of the Law, quite simply by the Decalogue, which is not the actual “Word", of Christ.—Emil Brunner, The Christian Doctrine of Creation and Redemption, 318