It was a Scottish king who gave the English the Bible in their own language, and the Authorised Version has had an incalculable influence on the culture and language of these islands for 400 years.

But despite that, and despite the fact that England has an established church, and that some of its bishops sit in the House of Lords, the notion that people in political life don't "do God" – as Alastair Campbell reminded Tony Blair – is not a particularly new one.

James VI and I's predecessor, Elizabeth I (whose father set up the Church of England, and whose godfather Thomas Cranmer had, along with William Tyndale and Myles Coverdale, paved the way for the King James Bible), declared that she had no desire to "make windows into men's souls".

Although there have been provocations from notable dissenters since, ranging from Jenny Geddes to Oliver Cromwell, Britain's political classes have, on the whole, tended to keep fairly quiet on the subject of religion. Lord Melbourne, who as prime minister reacted to an evangelical sermon by declaring: "Things have come to a pretty pass when religion is allowed to invade the sphere of private life," was perhaps an extreme example of this tendency.

Hence the excitable reaction to David Cameron's address at Christ Church in Oxford, celebrating the 400th anniversary of the Authorised Version, which was breathlessly described as a call for "a return to Christian moral values". In fact, as the transcript of his speech makes clear, it wasn't quite that.

Undaunted by this detail, secularists, possibly emboldened by the obituaries of the militant atheist Christopher Hitchens, rushed to denounce it. Equally predictably, it came in for criticism from some Christians for being too mealy mouthed and politically correct, and for name-checking outfits like Muslim Aid.

Mr Cameron really just maintained two things which ought to be unexceptionable. The first was that the United Kingdom is a Christian country, and the second that secular neutrality was undesirable. The reason they should be unexceptionable is that both statements came surrounded by caveats.

In the case of the first, Mr Cameron mostly talked about the way in which Christianity and the King James Bible have shaped the culture (including the politics) of Britain. As a statement of historical fact, that is self-evident.

He could have gone further. Advocates of secularism like to assume that agnostics or atheists are now a majority in this country, and religion a minority interest, but the evidence is against them.

In the 2001 census, 72% of the population described themselves as Christians and almost 6% as followers of other faiths, while only 15% said that they had no religion (I include amongst that group the 400,000 or so who gave their religion as "Jedi"). A fair proportion of that 72% probably aren't what most of us (whether Christians or not) would call Christian in any significant sense, but it is telling that they choose the label. When we get the results from this year's census next September, that may have come down a bit, but probably not by much.

Churchgoing has certainly declined in the last decade, though it is notoriously tricky to measure with accuracy, because there are so many different churches. The best records are for Church of England congregations, which have fallen by about 8% over that period, but attendance is actually rising in about a third of dioceses and amongst those under 16, and there are still more than 1.1 million people who attend Anglican services every week – considerably more people than the combined membership of political parties, or than those who go to football matches.

When one adds in Church of Scotland and Roman Catholic congregations (both of which have fallen less than the C of E), Baptists, Methodists, other free churches and the "charismatic" movement, which is growing very successfully, the best estimates suggest that almost 20% of the population attend church at least once a month, and probably at least that number consider themselves Christians although they seldom attend services.

And the global tendency is certainly not towards secularism: the proportion of the world's population which subscribes to one of the four main religions has increased from two-thirds to three-quarters.

Mr Cameron's other point – the danger of secular neutrality – does not, however, as he expressly pointed out, imply that faith is either necessary or sufficient for morality. One doesn't need to share all the late Mr Hitchens's views to notice that atheists can be moral, and that terrible things have be done in the name of religion.

But though the tradition of Christianity in Britain since the Authorised Version is one of steadily increasing tolerance, and our recent culture one of growing secularism, that is not the same thing as neutrality. Tolerance actively implies judgment, as well as the notion that no-one should police the beliefs of others, though they should be free to disapprove of them.

Actions, though, are a different matter. All sorts of anti-social behaviour – including that of religious extremists – have infected the body politic, and the Prime Minister is surely right to point out that a large part of the moral crisis in this country is a reluctance to speak out about the difference between right and wrong.

That can, of course, be done by those without religious faith, but it cannot be achieved by moral relativism or a neutrality which abandons the language, traditions, values and cultural norms which we have inherited. That inheritance is fundamentally Christian, and the fact that we live in a liberal society is due in no small measure to those values. Criminality, intolerance and anti-social behaviour have grown in direct response to our reluctance to insist on that tradition, and to employ the language of moral judgment.

Naturally, the King James Bible warned us about this: "Ye are the salt of the earth: but if the salt have lost his savour, wherewith shall it be salted? it is thenceforth good for nothing, but to be cast out, and to be trodden under foot of men."