Building on Augustine’s thought in The City of God, the political theology of most of the magisterial Reformers was some form of the “two kingdoms” doctrine as this excerpt from Philipp Melanchthon (1497–1560) shows. Here, he teaches that God ordained two distinct governments in the world—the temporal and the spiritual—and that both were essential and authoritative for the proper functioning of society. The rulers of the earthly kingdom administered external things such as life and property according to reason and sense, while the spiritual kingdom, consisting of all true Christians, governed the soul.

God Ordains Both Secular and Ecclesial Offices

It’s clear that God has ordered these two offices differently—the preaching office and worldly governing authority. And he has commanded that Christians must be under both offices. Thus, it’s a horrid error to mix these offices into one another or to remove and withdraw the one; for they are both God’s order and command. For absolutely no person has the power to overturn God’s order.

The Refutation of Several Unchristian Articles.

Romans 9-16, eds. Philip D. W. Krey and Peter D. S. Krey. Reformation Commentary on Scripture, NT Vol. VIII, p. 161.