History provides as many uncomfortable facts as science. Neither can be ignored if anyone is going to talk sense. Last week, the Prime Minister wrote rather movingly in the Church Times about his sense of this as a Christian country.
It followed up other comments from Cabinet ministers saying similar things, and finished on Tuesday with a very measured intervention by the attorney general, Dominic Grieve, whose own Christian faith is well known.
Judging by the reaction, anyone would think that the people concerned had at the same time suggested the return of the Inquisition (complete with comfy chairs for Monty Python fans), compulsory church going and universal tithes. More than 50 leading atheists wrote to the Telegraph in protest.
It's all quite baffling and at the same time quite encouraging. Christian faith is much more vulnerable to comfortable indifference than to hatred and opposition. It's also a variation on the normal "Sword and Grail discovered" stuff that seems to be a feature of Easter week news.
Yet the prime minister and other members of the government have not said anything very controversial. It is a historical fact (perhaps unwelcome to some, but true) that our main systems of ethics, the way we do law and justice, the values of society, how we decide what is fair, the protection of the poor, and most of the way we look at society... All have been shaped by and founded on Christianity. Add to that the foundation of many hospitals, the system of universal schooling, the presence of chaplains in prisons, and one could go on a long time. Then there is the literature, visual art, music and culture that have formed our understandings of beauty and worth since Anglo-Saxon days.
It is clear that, in the general sense of being founded in Christian faith, this is a Christian country. It is certainly not in terms of regular churchgoing, although altogether, across different denominations, some millions attend church services each week. Others of different backgrounds have also positively shaped our common heritage. But the language of what we are, what we care for and how we act is earthed in Christianity, and would remain so for many years even if the number of believers dropped out of sight (which they won't, in my opinion).
The atheist protesters are wrong to argue that expressing confidence in the country's Christian identity fosters alienation and division in our society. Indeed, it is significant that non-Christian faith leaders - among them Anil Bhanot of the Hindu Council UK, Farooq Murad of the Muslim Council of Britain and Lord Indarjit Singh of the Network of Sikh Organisations - have spoken out in support of Mr Cameron. Mr Murad said: "No one can deny that Britain remains largely a Christian country, with deep historical and structural links with the established Church... We respect that."
I know from personal experience that what Mr Murad says is entirely true. And I know that, as Iain Duncan Smith pointed out, the influence of a moderate and careful and generous Christian faith has enabled us to be welcoming to other faiths. That sense of generous hospitality provides the basis for tough discussion, and it is a hospitality that protects atheists as well, and so it should.
So why the fuss? As I say, for all of us, in the church, of Christian faith, of any tradition or set of beliefs, history makes for some uncomfortable reading. Its facts are awkward for all of us, but it is no use pretending they do not exist. The PM is right on this.
Justin Welby is the current and 105th Archbishop of Canterbury. This blog post first appeared on the Archbishop of Canterbury's personal blog, and can be viewed here