When Jesus came to Jerusalem for the last time before his crucifixion, his arrival was marked by a triumphant entry into the city and the crowds proclaiming Jesus as the messianic king (cf. Luke 19:28-40; Matthew 21:1-11; Mark 11:1-11). When the Pharisees failed to persuade the crowds from proclaiming such things, they changed strategies and tried to force Jesus to say something that would place him and his kingdom in conflict with the authority of Rome. In a series of three public interrogations the religious leaders of the Jews asked Jesus about his authority, the relation of his kingdom to civil government, and the relation of his kingdom to the family. 

The result was fascinating. While Jesus refused to answer the Jews' question about his authority, realizing that they knew well where his authority came from, he demonstrated that his kingdom is not in inherent conflict with the institutions of this world - whether government or the family - because it is of another age. To be sure, all authority in heaven and on earth has been given to Jesus (Matt 28:18), and one day these earthly institutions will pass away (1 Cor 7). But in the meantime, the order of this world continues. Therefore, "Render to Caesar the things that are Caesar's and to God the things that are God's" (Luke 20:25). What's more, "The sons of this age marry and are given in marriage, but those who are considered worthy to attain to that age and to the resurrection from the dead neither marry nor are given in marriage" (Luke 20:35). Christ is king but the order of creation, fallen as it may be, continues.

It is this distinction between the two ages, and between the institutions of one age and the kingdom of the age to come, that forms the foundation of the classic doctrine of the two kingdoms, as articulated by Martin Luther and John Calvin. The reformers argued that Christ governs and expands his kingdom through the ministry of the word by the power of the Holy Spirit. Yet, the reasoned, he does so in such a way as not to nullify the order of creation or the institutions that God has created to govern that order, most importantly those of civil government and the family. 

For Martin Luther, the two kingdoms doctrine was necessary in order to refute the longstanding claims of the papacy to hold all power, both spiritual and temporal, by virtue of the pope's office as the vicar of Christ. The Catholic "two swords" doctrine taught that the pope delegates the "temporal sword" to the magistrate on the condition that the magistrate exercises it obediently to the pope. Luther realized that on this basis magistrates were wrongly claiming the right to interfere with the gospel by virtue of their possession of the sword in service to the pope. Moreover, Luther continued, bishops were wrongly claiming the right to use the sword against the Protestant churches by virtue their own secular power. Only the two kingdoms doctrine, he insisted, could distinguish the secular purpose of the sword from the spiritual means by which the gospel is to go forth into the world. 

Luther tended to talk about the two kingdoms doctrine in three different ways. First, building on Augustine's two cities doctrine, he distinguished between those who serve God and those who serve the devil. Second, he spoke of two governments appointed by God to govern the world in which these two groups of people are mixed together: coercive government by the sword to maintain peace and basic justice in the world, and spiritual government by the word and Spirit to gather men and women into Christ's kingdom. Third, Luther often spoke of two realms, by which he meant the outward realm of the body and life in this world, and the inward realm of the eternal soul. To be sure, contrary to popular impressions, Luther did not believe Christians could live and act as if they were not Christians in the affairs of this world. He believed that believers are to live in love to their neighbors as servants of Christ, though in a manner compatible with their earthly vocations. It was Luther who said that a Christian prince is a rare bird in heaven.

Although the two kingdoms doctrine is often associated with Lutheranism, it actually played a crucial role in Calvin's thought as well. In addition to the basic Lutheran two kingdoms doctrine, which Calvin articulated in the 1536 edition of the Institutes, Calvin gradually articulated an understanding of the spiritual government of the church in distinction from the political government of this world. For Calvin, in contrast to both Luther and the Zwinglian branch of the Reformation, the church was to have its own pastors and elders who practiced church discipline ministerially and organized the basic elements of worship according to the word of Christ. In addition to the pastors and elders, Calvin argued for deacons who, in a spiritual manner distinct from that of civil government, cared for the needs of the poor. Calvin, like Luther before him, tended to use the two kingdoms doctrine to demonstrate why the Anabaptists were wrong in their insistence that Christians should never bear the sword. He also tried to show that those who thought Christianity overthrows the economic, social, or political structures of this age were misguided. 

Over time Calvin's two kingdoms doctrine came to characterize the confessional Reformed and Presbyterian traditions, particularly after Thomas Cartwright used it to defend the autonomy of the church from the royal supremacy of the English Queen Elizabeth I. Although Reformed Christians never arrived at unanimity on the political implications of the doctrine, it became absolutely foundational to their distinctive theology of the church.

In time, of course, this foundation was largely forgotten, though a version of it persisted as the Presbyterian doctrine of the spirituality of the church, and another version endured in the hearts of the Scottish Covenanters. In large part, the reason for this forgetfulness was that the challenge of the state against the church's autonomy and authority had evaporated. But in the late nineteenth century a new challenge arose. Protestant liberalism, particularly the version epitomized in the social gospel, sought to emphasize the immediate implications of the kingdom of Christ in this world. Any Protestant doctrine deemed too conservative, or too tolerant of the status quo, was minimized or abandoned. The kingdom of God, it was said, was to transform all of the institutions of this life, and this was to be the goal of all Christians in all their vocations, including politics.

The recent revival of interest in the two kingdoms doctrine is in large part explicable as a confessional Reformed response to this social gospel. A number of scholars and theologians have laid claim to the doctrine, while adjusting it to varying degrees to reflect developments in theology and politics (as well as personal convictions). Some contemporary two kingdoms advocates, particularly Darryl Hart, have stepped on the toes of many conservative evangelicals by arguing that the evangelical attitude toward the church and politics is often nothing better than a conservative version of the social gospel. In several books, including The Lost Soul of American Protestantism, A Secular Faith, and From Billy Graham to Sarah Palin, Hart has skillfully demonstrated the pietist post-millennial origins of both American evangelicalism and the social gospel, arguing that these groups have far more in common than most scholars would like to admit. In contrast, Hart argues, confessional Reformed Christians have always been much more careful not to identify the kingdom of God with social or political transformation. They have rightly recognized that the institutional expression of the kingdom in this age is the church, not the state, the family, or any other created institution. 

Part of the reason that Hart's version of the two kingdoms doctrine is somewhat controversial is that at times Hart has pressed the distinction between the two kingdoms to the point of separation. Indeed, if the classic two kingdoms doctrine denoted the difference between two ages and two governments, Hart has often written about it as if it amounted to a distinction between two airtight spheres, one the sphere of faith and religion, and the other the sphere of everyday life. While it is clear that Hart views these two spheres as expressions of the two ages, by speaking of them in terms of separate spheres he ends up downplaying the overlap between the two ages. This tendency becomes all the more marked in Hart's more polemical moments.

For instance, while Luther or Calvin argued that even in their vocations Christians serve Christ, are bound by his moral law, and are to do everything that they do in service to him, Hart sometimes speaks as if faith and Scripture have little to say about life in this world. To be sure, in key moments, Hart admits that Christianity does teach certain truths about the image of God or about the temporal nature of life in this world. For Hart, these are truths that should shape the way in which Christians engage politics. Indeed, Hart defends his very concept of secularity on the basis of orthodox Christian eschatology. Likewise, he acknowledges that Jesus is Lord over both the eternal and the temporal kingdoms, and that in every area of life Christians are to obey God according to their consciences. But often, Hart's criticism of the misuse to which American Protestants have framed Christian claims obscures these basic commitments. Part of the problem is that Hart says relatively little about the ongoing validity and binding authority of natural law, in contrast to classic versions of the two kingdoms doctrine, which include substantive accounts of natural law. This makes it possible at times to get the (false) impression that Hart thinks there is no determinative moral standard for Christian political or cultural engagement.

That said, Hart's historical critique of American evangelicalism is far more valid than many of his critics would like to believe. As a conversation I recently had with a prominent liberal evangelical ethicist suggests, Hart's criticism of mainstream Protestantism is much needed and can be very refreshing to those caught up in the politicization either of evangelicalism or of the mainline churches. His willingness to challenge the way in which Protestants simplistically conflate their own political preferences with the teachings of Scripture makes him an unpopular but needed correction to the hubris of Christian activists on both the right and the left.

A much more theologically substantive contemporary version of the two kingdoms doctrine is that of David VanDrunen. Like Hart, VanDrunen's initial work on the two kingdoms doctrine was historical. Unlike Hart, VanDrunen's target was not so much American evangelicalism as it was a brand of the neo-Calvinism that was so influential in the denomination in which he grew up.

In his Natural Law and the Two Kingdoms, VanDrunen argued that certain neo-Calvinists' emphasis on the role of human beings in establishing the kingdom of God through the transformation of every area of life was a break with the tradition's classic emphasis on the future and spiritual nature of Christ's kingdom, in contrast to the kingdom of this world. He argued that some neo-Calvinists have placed an illegitimate eschatological burden on the church by confusing the obligation of Christians to witness to the lordship of Christ, which Scripture requires, with an obligation to turn all of life into the kingdom. In short, VanDrunen argued, these neo-Calvinists have confused creation with redemption, forgetting that the new heavens and the new earth are caught up with Christ, and that they break into this age only in the church, however believers may witness to that reality in their daily lives.

In his more constructive theological work, Living in God's Two Kingdoms, VanDrunen offers a substantive exegetical argument for the two kingdoms doctrine. He argues that far too many Christians confuse their calling in keeping the creation mandate with Adam's task in fulfilling that mandate before he fell into sin. As a result, they continue to think of their cultural work as the work of bringing creation to its eschatological sabbath rest, failing to see that Jesus has definitively brought creation to its fulfillment in his death and resurrection. The task of believers in this age, he argues, is better thought of in terms of faithful obedience to Christ under the terms of the Noahic Covenant. Jesus establishes his kingdom. We merely witness to it.

Although VanDrunen also speaks of the two kingdoms in terms of two realms from time to time, he tends to be clearer than Hart that life in this age cannot neatly be divided into two spheres, one of which is religious and the other of which is not. He affirms that the antithesis runs through the temporal kingdom and that believers are to follow the teachings of Scripture in all that they do in their secular vocations, including politics. At the same time, like Hart, VanDrunen is quick to emphasize that Scripture does not give us the amount of precise instruction in these matters as many Christians would like to believe. And, like Hart, he thinks pastors need to keep politics out of the pulpit as much as possible, preaching only what is clearly taught in Scripture and leaving matters of application to the wisdom and consciences of believers. Unlike Hart, VanDrunen articulates (and is continuing to articulate) a rigorous doctrine of natural law that demonstrates the moral character of all of life under Christ's lordship. 

One of the emphases common to both Hart and VanDrunen is the importance of recognizing the importance of the church as the institutional expression of the kingdom of Christ in this age. The kingdom is otherworldly in the sense that it is future and its full consummation awaits Christ's return. The way in which we access that kingdom, they argue, is through the regular means of grace, specifically preaching and the administration of the sacraments. When we emphasize all of life as kingdom activity, just as when we view all of life as worship, we lose sight of what is distinctive and vital about the church itself. 

One of the ways in which modern advocates could strengthen the two kingdoms doctrine is by further emphasizing and clarifying its fundamentally eschatological character, particularly in light of the fact that the two kingdoms are often confused with two spheres into which life is to be divided. It may be that part of the problem is a conflation of the two kingdoms doctrine with Abraham Kuyper's concept of sphere sovereignty. But Kuyper's spheres denote different areas into which human life under Christ's lordship are to be divided; they do not designate the eschatological distinction between this age and the age to come. As such, the concept of sphere sovereignty is a sociological concept that is consistent with but different from the two kingdoms doctrine. We confuse the two when we think of the two kingdoms as two spheres (because they denote two governments) but forget that they also denote two overlapping ages. As 1 Corinthians 7 and Ephesians 5-6 make clear, because Christians live between two ages, they cannot turn everything they do into the kingdom of God, but they are to do everything that they do in obedience to Christ's lordship.