It seems to me that folk are in the habit of equivocating on the term “two kingdoms,” thus introducing a measure of confusion to discussions on this topic. I’ve seen this in articles and books, particularly when looking at historic precursors for modern articulations of “two kingdoms” views. The language of “two kingdoms” is just accidental, obviously it’s the essence of the distinction that matters. Unfortunately, there is a certain level of arbitrariness depending on how one uses the terms.

In Heiko Oberman’s Forerunners of the Reformation, he introduces terminology to distinguish between two ways of understanding the relationship between Scripture and tradition in medieval thought. He termed these “Tradition I” and “Tradition II” (one being the Protestant view, the other Roman Catholic). But this is just a tangent to explain how I came up with an idea for something similar when talking about “two kingdoms.” I’ve found three different ways of using this terminology.

Two Kingdoms I. A distinction between God’s kingdom and Satan’s kingdom, between the kingdom of light and the kingdom of darkness. There is here a definite hostility between one and the other. Here is a distinction between all who are in Christ and in Adam, the believing church and unbelieving world, or between the elect and the reprobate. And so it is obvious that an individual may only be a member of one or the other kingdom, not both. A few examples:

Augustine, The City of God, XI.1 (available here): The city of God we speak of is the same to which testimony is borne by that Scripture, which excels all the writings of all nations by its divine authority, and has brought under its influence all kinds of minds, and this not by a casual intellectual movement, but obviously by an express providential arrangement. For there it is written, “Glorious things are spoken of thee, O city of God.” And in another psalm we read, “Great is the Lord, and greatly to be praised in the city of our God, in the mountain of His holiness, increasing the joy of the whole earth.” And, a little after, in the same psalm, “As we have heard, so have we seen in the city of the Lord of hosts, in the city of our God. God has established it for ever.” And in another, “There is a river the streams whereof shall make glad the city of our God, the holy place of the tabernacles of the Most High. God is in the midst of her, she shall not be moved.” From these and similar testimonies, all of which it were tedious to cite, we have learned that there is a city of God, and its Founder has inspired us with a love which makes us covet its citizenship. To this Founder of the holy city the citizens of the earthly city prefer their own gods, not knowing that He is the God of gods, not of false, i.e., of impious and proud gods, who, being deprived of His unchangeable and freely communicated light, and so reduced to a kind of poverty-stricken power, eagerly grasp at their own private privileges, and seek divine honors from their deluded subjects; but of the pious and holy gods, who are better pleased to submit themselves to one, than to subject many to themselves, and who would rather worship God than be worshipped as God. But to the enemies of this city we have replied in the ten preceding books, according to our ability and the help afforded by our Lord and King. Now, recognizing what is expected of me, and not unmindful of my promise, and relying, too, on the same succor, I will endeavor to treat of the origin, and progress, and deserved destinies of the two cities (the earthly and the heavenly, to wit), which, as we said, are in this present world commingled, and as it were entangled together. And, first, I will explain how the foundations of these two cities were originally laid, in the difference that arose among the angels.

Caspar Olevianus, Exposition of the Apostles’ Creed (quoted here): For it is certain that there are two Spiritual kingdoms in this world, to wit, a kingdom of darkness and and kingdom of light: and it is necessarily the case that every man lives in or the other of them.

Westminster Shorter Catechism
Q. 102. What do we pray for in the second petition?
A. In the second petition, which is, Thy kingdom come, we pray that Satan’s kingdom may be destroyed; and that the kingdom of grace may be advanced, ourselves and others brought into it, and kept in it; and that the kingdom of glory may be hastened.

It is worth noting that the Westminster Standards only ever use the word “kingdom” in this sense.

Two Kingdoms II: A distinction between the visible church and the civil government. Between these two “kingdoms” there need not be hostility, though there may be (Rome persecuted the church). But they are not intrinsically opposed the one to the other (since God has instituted both the church and the state). An individual, if a Christian and a civil servant, will be a member of both (e.g., Constantine, Abraham Kuyper). While an unbeliever could only be a member of the civil government if having an appropriate office and most Christians are only members of the visible church. And some individuals are not members of either the church or the civil government.

The Westminster Standards make this distinction between the church and the civil magistrate, but (1) never refer to the civil magistrate as a “kingdom” and (2) never speak of the civil magistrate as a “realm” to be governed by natural law. The Confession of Faith (I subscribe to the American Revisions) speaks of “ecclesiastical” and “civil,” but when it refers to “civil” it is always to the actual state and not a “moral realm.” For example, see WCF 20.4, in which it is confessed that “they who, upon pretense of Christian liberty, shall oppose any lawful power, or the lawful exercise of it, whether it be civil or ecclesiastical, resist the ordinance of God.” Here “civil” is not a realm of life, it is an actual social institution ordained by God with authority.

Two Kingdoms III: A distinction between what is to be governed by special revelation (the “spiritual kingdom,” which offers salvation) and that which is to be governed by general revelation (the “civil kingdom,” which offers a universal ethic via natural law). In this case everyone is a member of the “civil kingdom,” and only Christians are additionally members of the “spiritual kingdom.” Again, there is no essential hostility between these two kingdoms because, it is argued, God is the author of special and general revelation. I will give one example of this view:

David VanDrunen, A Biblical Case for Natural Law, p. 37: The doctrine of the two kingdoms teaches the existence of a civil realm in which all human beings, of whatever religious commitment, are to intermingle and cooperate in pursuit of cultural progress. One affirmation about this realm … is that it is a moral realm. On the one hand, the civil kingdom is not a religious realm in the sense that it concerns temporal affairs rather than affairs of salvation and eternal life, but it stands under the authority of God, its creator and sustainer. As King of the civil realm, God holds it under moral obligation. On the other hand, because the civil kingdom is common to the human race, it is not morally neutral. … God ordains the civil kingdom to be a realm in which justice is administered and in which the creation ordinance of filling the earth is pursued (Gen. 4:15; 9:1, 5-7). Moral goods such as peace and prosperity are to be cultivated (Jer. 29:7). Civil magistrates exist for the good of the people, and the people are to obey civil magistrates (Rom. 13:1-7; 1 Tim. 2:2; 1 Peter 2:13-17). These are just a few examples of the moral responsibilities that continue to exist in the civil kingdom.

As is obvious in the quote, the “civil kingdom” in this view is not synonymous with the civil magistrate, although the civil magistrate is a part of it. It is clearly no longer an “institution” (like an actual state government) but is a “moral realm” that all persons are members of. The authority in this realm, as VanDrunen argues in the book, is not the civil magistrate per se (as in Two Kingdoms II) but natural law. The authority of the “spiritual kingdom,” the church, is Scripture. I see no precedent for this view in the Westminster Standards.

Concluding Thoughts

If the word “kingdom” can refer to a realm or region in which something is dominant, then obviously it can be used in all sorts of different contexts: The kingdom of God (in which God rules), the kingdom of Satan (where Satan rules), the kingdom of the state (variously termed, in which this or that civil magistrate rules), the kingdom of the family (in which the husband rules), the kingdom of the school (in which the headmaster rules), and even the kingdom of natural law (variously termed, in which natural law is to rule). These are just realms or spheres, each with their own legitimate structure, authorities, etc. Some are “moral realms” and therefore essentially invisible (the moral realm of natural law), some are institutions that have physical manifestations (the church and the state).

And so if any given theologian uses the language of “two kingdoms” it is absolutely essential to determine what he means by the word “kingdom” before pointing to the theologian as a representative of your or another’s view. Given the nature of the language “two kingdoms,” it is conceivable that the same author could speak of both Two Kingdoms I and Two Kingdoms II. I don’t recall seeing any historic Reformed theologians using the Two Kingdoms III distinction, but I’d modify my post to include references/quotes if anyone produces any. Someone like Calvin, obviously, distinguishes between God’s kingdom and Satan’s kingdom and, at the same time, distinguish between the church and the state. But it doesn’t follow that Calvin therefore adhered to the Two Kingdoms III view.

Furthermore, to claim that either the Two Kingdoms I or Two Kingdoms II distinctions is an earlier development of the other seems to miss the point. Both of these are legitimate distinctions. God’s kingdom is distinct from Satan’s and the church is distinct from the state. These aren’t really related except that the same language is sometimes used in regards to both ideas, and of course God’s kingdom is in a measure the same as his church. And so when looking for a historic precedent for a certain view, it is important to keep these two views distinct and not commingle them. Regarding the Two Kingdoms III view, it may have conceivably risen as a development of Two Kingdoms II, but making that sort of a historical judgment is beyond the scope of this post.