What should Christians expect of human politics? Should we pursue Christian ends by political means when the opportunity arises? If there’s one figure in church history who gets a bad rap, it’s Constantine, the Emperor of Rome who apparently converted to Christianity in 312. Or at least, something like that: history is of course more complicated than we think.

The famous story goes that on the eve of the battle of the Milvian Bridge (28th October, 312 AD), Constantine had some kind of vision or dream (the contemporary sources seem to disagree) which led him to paint the shields of his soldiers with the labarum. The labarum was a sign which combined the Greek letters ‘Chi’ and ‘Rho’, which look like an ‘X’ and a ‘P’, and which form the first two letters of the name of Christ.

Constantine won the battle, and this led to an extraordinary change in the policy of the Empire. Constantine’s predecessor Diocletian (284-305) had unleashed a terrible persecution against the Christians in an attempt to placate the Roman gods. Rome was under pressure from all sides, and Diocletian hoped to restore her fortunes by his policy.

So Constantine’s ‘conversion’ was a radical about face. Was this merely the cynical, calculating move of a skillful politician? Although he did not accept baptism until close to his death, he certainly identified as Christian and allowed his Imperial icons – his coins and other images - to be become gradually more Christianised. He intervened directly in church affairs, and even summoned the council of Nicea in 325. He was given to preaching sermons. He supported the church financially, and built many churches including the Church of the Holy Sepulchre in Jerusalem. According to some writers, this was the moment that Christianity went from being a movement of authentic faith and of witness to the rule of Christ to a ‘state’ religion. At this moment, Christianity became intertwined with the power and wealth of Rome.

In Constantine and in his successors it found an advocate who would pursue its interests with all the apparatus of Imperial power including the sword. Was this really what the movement begun by a Galilean peasant and preached by a Jewish itinerant preacher had come down to? It has proved a difficult habit to give up. The Mennonite theologian John Howard Yoder coined the term ‘Constantinianism’ to describe the way in which, even today, Christians continue to pursue the mission of Jesus Christ through the political power of the nation-state, and through force of arms. Yoder argued that this was entirely contrary to the essence of the Christian message. This might take the form of American evangelicals co-opting the Republican party as their political wing, or the way in which the Church of England is still run as a bureaucracy of the British state. In particular, Yoder argued that early Christianity was uniformly and adamantly pacifist. It was only with the Constantinian turn that Christians started to justify going to war.

But a new book by American Reformed theologian Peter Leithart, Defending Constantine – The Twilight of Empire and the Dawn of Christendom, puts the opposite case. Leithart seeks to defend Constantine as a historical figure from the charges of using Christianity out of manipulative cynicism; and also to defend him as a model of Christian politics. Constantine was not a theologian, and his faith was sometimes simple, but he clearly believed that the Christian God was the providential Judge. He would vindicate the righteous and put down the wicked. By its unity, the Christian church would offer pleasing worship to God and be an effective instrument of mission.

Leithart has a good deal of sympathy for Yoder, as surely we must. There is much that is ugly and unchristian about some of the collaborations between state and church that we know from history. But are we to think that God was not active in those rulers who, over a period of 1500 years, identified as Christian? Was none of them a sincere believer? Has the Bible nothing to say about the business of ruling to the ruler who wishes to come forward for baptism – or to the society which decides that it wants to pursue a Christian path (as many have)?

The problem is not with the notion of a Christianised politics (for Leithart), but that Christian politics has more often failed to live up to its own gospel. Leithart writes: “If there is going to be a Christian politics, it is going to have to be an evangelical Christian politics, one that places Jesus, his cross and his resurrection at the center. It will not do to dismiss the Sermon on the Mount with a wave of the hand (‘that’s for personal life, not political life’) (p. 332)

That is: if we are going to elect Christian politicians, or urge the state to pursue Christian policies, then we’d better not be half-hearted about it! Why, for example, have we in the church permitted politicians who are Christian by subscription or conviction to enact policies that are so degrading of our common life as a nation? How is love for neighbour being expressed in Australian politics at the moment? Why do we put up with less than honest politicians? Why is generosity so lacking in Australia?

I am not expert enough to judge whether Leithart has got his history right. There are many controversial questions in the life of Constantine that will never be resolved at this distance. But he makes a compelling theological case about the possibility of a Christianised politics – one that ought to be carefully considered. The influence of the gospel for the better on contemporary society has occurred not merely from outside the political arena as a prophetic voice but from within it.

(Feature photo credit: York Minster)