When our Lord mentioned the words “render to Caesar the things that are Caesar’s, and to God the things that are God’s” (Matt. 22:21, ESV), many wished that Jesus would have said more. What exactly are the things that belong to Caesar, and what are the things that belong to God?
Jesus’ brevity is understandable, given that he spoke just enough to defuse the trap that the religious leaders of his day sought to entangle him in. Instead, it is up to the church down her history to figure and flesh out the details of Jesus’ statement and, along with that, the posture the church should take in regard to Church-State relations.
I believe that one valuable resource to guide our thinking in this area comes from the pen of John Calvin (1509–1564), pastor and reformer in Geneva during the Protestant Reformation.
To be sure, Calvin wrote in a political and social milieu markedly different from ours. He wrote within the context of the Christian commonwealth of Geneva — the latter broadly defined as a Christian society in which civil and ecclesiastical powers work together in cultivating “true religion” and promoting the welfare of the body politic. This context, as one can obviously tell, is a context vastly different from our religiously and politically pluralistic societies today, which often have secular governments helming the governance of the nation.
However, as some have argued, the true value of what Calvin has to offer lies not in his political actions or specific political opinions but in his political theology. That is to say, it is Calvin’s theological and ethical account of human life and society, and how that account shapes our understanding of the church, civil government, and other social institutions, that contains the gem of what Calvin has to offer.
Getting to the crux of Calvin’s political theology requires one, in turn, to pay attention to his two kingdoms doctrine, for it is this doctrine that grounds and leads to Calvin’s political theology.
Stated simply: the two kingdoms doctrine is Calvin’s distinguishing between Christ’s lordship over his eternal kingdom and the temporal affairs of this life, which fall under the temporal kingdom. Inasmuch as we tend to conceive the two kingdoms as denoting different spheres of influence or different institutions, the character of the doctrine is first and foremost eschatological in nature. All the terms Calvin utilizes to describe the two kingdoms — spiritual/temporal, heavenly/earthly, soul/body, inward/outward, and ecclesiastical/political — are thoroughly eschatological by nature in Calvin’s usage.
The eternal kingdom, for Calvin, is really an eschatological reality concerning the restoration of the entire creation that stems from the regeneration of human beings through Christ’s word and the Spirit. This creation-wide restoration begins in the church, and in this present age, this eternal kingdom is realized only through the spiritual government that the Lord exercises in the church through his ministers.
Through his two kingdoms doctrine, Calvin thus distinguishes the church from the temporal and political affairs of life, albeit not in a hermetically sealed fashion, but in a manner that accords to each sphere its own form of jurisdiction or government.
It is this fundamental differentiation between the two kingdoms of Christ that leads to Calvin’s programmatic statement in the Institutes of the Christian Religion:
[T]here is a twofold government in man: one aspect is spiritual, whereby the conscience is instructed in piety and in reverencing God; the second is political, whereby man is educated for the duties of humanity and citizenship that must be maintained among men (Inst. 3.19.15).
Calvin’s extended treatment of the first form of government (the “spiritual”) is found in Inst. Book 4 Chapter 3, while that of the second form of government (the “political”) is found in Book 4 Chapter 20.
The chief utility of Calvin’s distinguishing between spiritual government and political government is that the boundaries of each governmental realm, and consequently their function and role, become clearly defined.
Spiritual government is concerned with the restoration of true spiritual righteousness, virtue and eternal life in humanity, while political government with establishing civil righteousness and — within the context of the Genevan commonwealth — the outward worship and defense of true religion in accordance with love and prudence (Inst. 4.20.2).
The clearly demarcated boundaries with each governmental realm leads to an appropriate circumscription of authority.
Temporal or magisterial authority through the office of the civil government is not meant and is not able to bring about a true inward righteousness and piety associated with salvation from sin, yet civil government is necessary to preserve outward piety and order while awaiting the consummation.
Similarly, because spiritual or ministerial authority mediates the spiritual kingdom to believers in this time and age, the office of the pastor is to focus on faithfully ministering Christ’s word and the sacraments, and in enforcing church discipline. As to the other area of how the church is to conduct herself as an institution in the political kingdom, that is to be left under the jurisdiction of the civil authorities.
In short, as Calvin himself states: “The church does not assume what is proper to the magistrate; nor can the magistrate execute what is carried out by the church” (Inst. 4.11.3).
Having outlined the broad framework of Calvin’s overall political theology, I would like to share four insights as to how his thoughts can guide our own thinking in this area of Church-State relations.
First, Calvin highly esteemed civil jurisdiction and authority. Although it is unable to bring about true inward righteousness and piety, Calvin nowhere denigrates civil authority. For him, the distinction between the two governments lies not in a matter of inferiority or superiority, but in simply recognizing their difference.
Calvin sees magistrates as equally ordained by God, going so far as to describe civil authority as a most sacred and honorable calling among men (Inst. 4.20.4); he cautions against paying respect to the civil authorities only because we see them as a form of necessary evil (Inst. 4.20.22), and he calls for an obedience among the people characterized by restraint and almost passivity when it comes to political action (Inst. 4.20.23). Calvin extends the injunction to obey even to the unjust magistrate, as long as such obedience does not result in disobedience to God (Inst. 4.20.24 and 4.20.32). What seems like Calvin’s totalizing call for submission to civil authorities flows from his doctrine of providence — Calvin firmly believes that it is God who has ordained his magistrates.
Second, Calvin’s two kingdoms political theology provides a realistic picture of both church and state, grounding our understanding of Church-State relations in a form of Christian realism deeply rooted in an orthodox and scriptural foundation.
Civil government is not the kingdom of Christ, and it should not be rendered so. The civil law from which magistrates operate is not only unable to establish spiritual righteousness, but often has to tolerate sin and sometimes even regulate sinful practices so as to mitigate their most destructive consequences. Civil government is not delegitimized when it fails to comply with the moral standards of God’s law, nor should it be required to do so.
Likewise, even as spiritual government leads to true inward righteousness, the church must refrain from dictating the way in which the laws of the land are to reflect that righteousness; spiritual or ecclesiastical government must not overextend its authority into that of the temporal or political government.
Third, Calvin’s preference in turning to natural law rather than the Law of Moses in framing moral discourse (Inst. 4.20.14–16) — even within a Christian commonwealth! — provides a valuable insight as to how we can conduct moral discourse within pluralistic societies today. This is important because moral discourse inevitably grounds much of the political deliberation and policies that are enforced by governments.
In this area, it is interesting to note that Calvin did not insist on conformity to the Old Testament’s civil law, advocating instead the rigorous use of reason, experience, pagan political philosophy and the laws of nations in tandem with scripture as his mode of moral and political reasoning.
In so doing Calvin not only rules out theonomy as a vision for societies, but he upholds natural law, which he identifies as the law of love and the rule of equity, as a basis by which Christians can engage in public engagement in the varying contexts they find themselves in, be it religiously diverse or secular societies.
Furthermore, using natural law also does not indicate that Christians have surrendered biblical norms and values. As Calvin saw it, the final authority concerning the content of natural law is still scripture. But because natural law can be known through reason, the sciences, experience and conscience, it offers Christians a means of participating meaningfully in moral and political discourse without either preaching at nonbelievers or putting Christian confession as a prerequisite for discussion. It provides us with a common ground, a “public reason” to further dialogue.
Fourth, when lifted from its context of a Christian commonwealth and transported to many of our religiously pluralistic societies today, I wonder if Calvin’s description of the role of civil government in establishing civil righteousness, protecting the outward worship of God and defending sound doctrines of piety could be extended to argue that it is incumbent upon governments today to likewise provide a conducive environment for the flourishing of religions.
I add immediately that in offering this suggestion I am venturing and perhaps even stretching the very limits of Calvin’s thoughts, but I envisage no other way for Calvin’s conception of the role of civil government to find an application and place in today’s political contexts which are vastly different from that of Calvin’s day and age. If, as Calvin understood it, the purpose of civil government is to rule for the common good through the flourishing of true religion, then, in our unique political landscape consisting of religiously pluralistic societies often backed by secular governments, achieving that ideal might come through the common flourishing of religions.
 This idea is cogently argued by Matthew J. Tuininga, Calvin’s Political Theology and the Public Engagement of the Church (Cambridge: Cambridge University Press, 2017). Having said the above, Calvin did offer his political opinions at certain points, for example, how he saw a political system compounded of aristocracy and democracy excelling others (Inst. 4.20.8).
 I am using the term “public reason” here in the sense of how it is commonly understood in political philosophy to refer to the moral ideal of a common or shared framework used in political deliberation within liberal democratic societies that is reasonably justifiable or acceptable from each political interlocutor’s viewpoint.