It used to be so easy. Britain was a Christian country, based on Christian values, populated by Christian people, who had Christian values. The answer to the title question was simple: “The dominant one”.

Some still respond thus today, but few can deny that things have changed. Britain is no longer (as) Christian as it once was. Some contend that it is no longer Christian at all, that its very deep Christian roots are largely irrelevant today, and that the answer should be: “Preferably none. Faith is private and should remain private.”

In truth, the “privatisation” argument is hardly more convincing than the “Christian nation” one. In spite of how you might wriggle, the fact remains that in the privacy of their own homes, free from any immediate peer pressure, given eight options to choose from, the first of which was ‘None’, and being alerted to the fact that the question was voluntary, 37 million people in England and Wales chose to say they belonged to the Christian religion at the last Census. You cannot discount this any more than you can discount the impact of 1,400 years of Christian history.

So, if the answer isn’t “the dominant one” or “preferably none”, what is it?

The answer lies, strangely, not with Christians but with the state in which they operate. Christians will do what they understand Christ calls them to. The Church’s agenda will be set by the gospel not by any particular government. The fact that Christians disagree on the nature of that call hardly helps matters. But, their differences aside, few Christians deny that Christianity is a public religion and the gospel public truth. Short of state intervention like that of the Soviet Union, whether the Christian faith has a public face is not up for debate.

Rather the question is where that public face should be seen: in partnership with, largely without, or even actively against the governing authorities?

In as far as the New Testament advocates any particular position on this, it is one of flexibility. There is no blueprint for the Church’s relationship with the governing authorities that should hold for all times and in all places.

This is because the nature of the state in which Christians find themselves will vary radically, and they need to be able to respond accordingly. Hence, the answer to the title question is dependant not on the church but on the state. If the governing authorities behave in such a way as is consonant with the gospel – if, for example, they judge justly, maintain public order and seek to help the vulnerable – then there is real opportunity for partnership. If, on the other hand, the authorities are, for example, corrupt or recklessly libertarian or aggressively imperialist, they would not find much in Christian public life that they would wish to encourage, and the relationship will be far more antagonistic. The question is in which moral direction is the state facing.

In modern Britain this is a fiendishly difficult question. Historical influences, radically plural public opinion, frequently un-joined-up policy making… all such factors combine to make the moral orientation of the British governing authorities varied and complex.

In spite of this, the principles underlying the moral orientation of the British governing authorities are instructive. Because populations do not profess a single, identifiable conception of the public good, democratic governing authorities cannot reflect what isn’t there. Instead, in the UK at least, they develop manifestos, which embody conceptions of the good, which are then presented to the public who choose between them. This is the key to understanding the church’s proper role in the public square.

The church is not a political party and should never tout for votes. Moreover, at the risk of repetition, as long as there is a church, that church will be a public body. No amount of state intervention or low level secular bullying will change that.

However, what role it plays in the public square does and will change according to the nature of that public square. In the UK the nature of the public square is not determined simply by public choice. If it were, both euthanasia and the death penalty would be sanctioned. Rather, it is determined by warring concepts of the public good, which are more or less approved or disapproved by the public in various different ways.

The role of Christianity in contemporary Britain should be decided according to this principle: not on the desire of some for unmerited privilege or of others for sinister privatisation, but on the extent to which Christians can persuade the British public that “Doing God” does, in fact, contribute to the public good.

Nick Spencer is Director of Studies at Theos, and author of the latest Theos report Neither Private nor Privileged, The Role of Chirstianity in Britain Today.