Someone asked me recently about my views on church and state. I replied that I advocate a "Christendom model" of church-state relations. Then I proceeded to qualify. When I was done qualifying, I suddenly wondered whether what I call "Christendom" corresponds to what other people understand by the word. It seems a useful exercise to discriminate what Christendom gets right and what it gets wrong. One of the sources of ambiguity is that Christendom can be used both to describe a theoretical ideal of Christian politics and to describe an actual political order and civilization. The two senses are related, in that the theoretical ideal abstracts from the mess of the historical phenomenon. Yet they are distinct, and blurring the distinction produces confusion. In what follows, I'll try to keep the distinction in view. For starters, what Christendom gets right. Christendom involves the effort to conform public life to the gospel and the word of God. Christendom is an historical and political expression of the kingship of Christ. Christendom has been evident in, for instance, coronation rites that invoke the Triune God, treatises on godly rule that stress the ruler's imitatio Christi, legal codes that cite or are rooted in Scripture. In this sense, Christendom is inherent in the gospel. Yahweh promised Abraham that kings would come from him. Psalm 2 proclaims that the Lord has set His anointed at His right hand to rule the nations, and the New Testament explicitly applies this Psalm to Jesus (the resurrection in particular, Acts 13). Paul preaches the gospel of the son of David in order to bring about the "obedience of faith" among the Gentiles (Romans 1). As Oliver O'Donovan has stressed, Christendom fulfills the gospel as the response of the nations to the authority of Jesus. Christendom aims to embody the vision of this prayer, taken from the Lutheran Service Book & Hymnal: "O God our Father, who hast promised that the kingdoms of this world shall become the kingdom of thy Son: Purge the nations of error and corruption; overthrow the power of sin, and establish the kingdom of grace in every land; incline the hearts of all rulers and peoples to the Lord of lords and King of glory, that he may enter into their cities, churches, and homes, to dwell there and govern all things by his word and Holy Spirit; through Jesus Christ our Lord. Amen." Christendom is also right to recognize the church as the body of Christ. At its best, historic Christendom has acknowledged the church as a unique and independent religious society. Constantine facilitated the assembly of the council of Nicea, but did not (in my judgment) control its results. In acknowledging the church as the body of Christ, Christendom's rulers have also respected the church as God's spokesman. Ambrose rebuked Theodosius for his brutality in war; more ambiguously, Gregory VII brought Henry to heel. In the best cases, the church played a prophetic role in historic Christendom. But Christendom has also gotten things wrong. For some, such state sponsorship of the church is the essence of Christendom: Tax funds collected by the coercive state are funnelled to pay the salaries of clergy and to pay other church expenses. But there are always strings attached. Constantine didn't control the internal operations of the church, but his generosity in sponsoring the church made the church somewhat dependent on state funds and created perverse incentives for church leaders. Only the hardiest of church leaders are willing to bite the hands that pays for their meals. These pressures are particularly acute in post-Reformation versions of Christendom, when the established church often becomes a virtual department of state, losing virtually all of its independence. Taking on the role of "chaplain," the church mutes its prophetic witness. This post-Reformation version of Christendom is a defection from the earlier models of Christendom. Insofar as the church was absorbed into the state, it undermined one of the founding principles of late Roman and medieval Western Christendom - the independence of the church. Absorption of the church into the state is a reversion to pre-Christian pagan arrangements of religious politics. Under Christendom, state authorities have enforced religious orthodoxy. This goes back to the founding of Christendom: Constantine did not determine the outcome of the Nicene Council, but he enforced the results. In some cases, political authorities adjudicate what counts as orthodoxy. Again, for many this is an essential feature of Christendom, but it stands in sharp tension with another, fundamental feature of Christendom - the acknowledgment of the church as an independent religious society. The problems of Christendom are well illustrated by the Westminster Confession's treatment of the civil magistrate. Chapter 23.3 states: "Civil magistrates may not assume to themselves the administration of the Word and sacraments; or the power of the keys of the kingdom of heaven; yet he has authority, and it is his duty, to take order that unity and peace be preserved in the Church, that the truth of God be kept pure and entire, that all blasphemies and heresies be suppressed, all corruptions and abuses in worship and discipline prevented or reformed, and all the ordinances of God duly settled, administrated, and observed. For the better effecting whereof, he has power to call synods, to be present at them and to provide that whatsoever is transacted in them be according to the mind of God." On the one hand, the Confession aims to protect the independence of the church as the ministry of word, sacraments, and discipline. The challenges come to the fore with the statement that the magistrate has authority to advance the unity and peace of the church, protect the purity of truth and suppress heresy and abuses of worship. How is the magistrate to judge such things? Conflict might break out because reformers are trying to correct a corrupt church; on which side should the magistrate land? And, again, how does he know? How does a magistrate do what the Confession encourages without effectively subordinating the church to the state? Civil rulers should promote the spiritual as well as the physical health of the people they govern. They should encourage true piety and worship. But with what tools? Should Congress send troops in to break up a worship service that is full of abuses? Or should they discourage heresy through tax policy? Or should rulers encourage the church to maintain her own purity and peace? No church-state settlement settles things, certainly not forever and always. History upends the best-developed theories. The history of Christian politics has been and will always be a messy history. But we can lay out some basic guidelines: The church is the body of Christ; that is the truth, and states are better off when they acknowledge the truth. Rulers are better off when they listen to those whom God has called to teach His word. But the burden of Christian politics lies with the church, not the state. As the body of Christ, the church is the present outpost of the eschatology city of God, an independent polity. Christendom as a historic polity has deviated from Christendom as a theoretical ideal when the church has failed to live out the truth about herself.