Dear Archbishop Rowan,

Even though I’m not sending Christmas cards this year – ran out of time – you are not going to escape my seasonal circular letter. It is filled not with the record of my many achievements, holidays taken, operations survived and the GCSE results of my imaginary children, but instead has a few tidings of great joy, because you seem to need them at the moment.

You sounded a bit down the other day when you were talking to the Daily Telegraph, complaining that our government assumes “that religion is a problem, an eccentricity practised by oddities, foreigners and minorities”. Well, the government is often right about that, so if I were you I wouldn’t worry about it too much. I’d be more worried if the government didn’t think religion was a problem.

The Telegraph came up with more why-oh-why material last week, publishing the results of a survey indicating that only half those questioned in this country called themselves Christian. I wouldn’t pay too much attention to that either. God will no doubt cope. Let me draw on the words of the Blessed Ian Dury and give you some reasons to be cheerful: one, two, three.

The first reason is the established Church of England. It’s true, as that Telegraph survey suggests, that it’s not what it was, and the change has been astonishingly quick – encompassing my own still not over-prolonged lifetime. When my father, an Anglican parson, moved in the mid-1950s to become rector of a little country parish in Suffolk, there were still old ladies who would curtsy to him in the street, just because he was the rector.

Worldly power has gone out of the established church, and that is why so many of its adherents have fallen away. Thank goodness for that; churches never handle power well. Think what 1950s England was like when you and I were small boys: the stodgy conformity, the sexual hypocrisy, the complacent, monochrome white Anglo-Saxon Protestant culture. The Church of England, in its funny, messy, unwitting way, helped us to get out of that – giving vital help, for instance, to the tentative and much opposed moves in that same decade to decriminalise homosexuality. Compare the grim-faced, negative reaction of the Roman Catholic church in Spain in recent years to new freedoms as democratic Spain has thrown off General Franco’s legacy; give public thanks for the Church of England’s bumbling liberalism.

The C of E doesn’t deliver strident moral or doctrinal judgments to make an easy headline. Journalists and broadcasters often sneer at such indecisiveness, even though rarely would they be inclined to subject themselves to any system of moral stridency. The history of Anglicanism is confused and contradictory, and because the C of E never succeeded in achieving the monopoly over national religion that it undoubtedly sought, the church has become an icon of diversity and plurality for the nation.

Its doctrinal statement, the Thirty-nine Articles of Religion of 1563, is pleasantly anchored in past history, fighting ancient battles. Any Anglican would be happy to acknowledge the importance of such history, while not having to believe personally, for instance, that “the laws of the Realm may punish Christian men with death for heinous and grievous offences”. Instead, this established church can be a home for those who go to it to express their doubts as well as their faith. It can be a shelter also for the kaleidoscope of culture, faith and no faith that now makes up our cheerfully diverse nation: an inoculation against the fanatics, both religious and anti-religious.

As the Scots, Welsh and Northern Irish withdraw into their own search for national identities, please tell the English, whoever they are, to cherish this ecclesiastical symbol of a rainbow nation. At the moment the English church is afflicted by humourless, tidy-minded souls who want everyone in it to think just like them, and who frequently use the Bible to achieve their aim in the manner of a blunt instrument in an Agatha Christie mystery. Resist them, firm in the faith! Remember what Neil Kinnock achieved against the entryism of Militant in the Labour party of the 1980s. You and archbishop John Sentamu could together witness in the same way for sanity in the C of E.

My second reason to be cheerful is the ordination of women in the Anglican priesthood. Anglicans were the first episcopally governed church grouping to ordain women, way back in the Second World War, in a dire emergency in Japanese-occupied Hong Kong, when the only person available to do one priestly job was a woman, Florence Li Tim-Oi. Loud were the condemnations then, and there has been much angry noise since. But what riches the Church of England has gained since it joined sister-Anglican churches in ordaining women in 1994!

Women priests have faced some extraordinarily childish behaviour from many male counterparts: bullying, condescension and frank undervaluing of their ministry. Besides this has been the glass ceiling that prevented them from being eligible for choice as bishops. Now all that is about to change, and not least among the considerations behind the General Synod’s overwhelming vote for change has been the grace so many women have displayed in the face of masculine bad manners. But there is also an everyday grace that women have brought to the ministry: a general reluctance to join in the theological party strife so common among male clergy, who like nothing better than to line up as Anglo-Catholics or evangelicals, as if they were a set of football hooligans out on the streets after the match.

Consider, Archbishop Rowan, that one of the most positive images of the Anglican parish priest in the English media is the now evergreen Vicar of Dibley. There’s what the Great English Public think of their women clergy: a bit daft, fond of a box of chocolates or two, but, underneath it all, a source of love and common sense for a community that always has the potential to behave badly. When you think of some of the other stereotypes of priests around at the moment in these islands or beyond, just thank your lucky stars for the folksy silliness of the vicar of Dibley.

My third reason is the election of a bishop in a diocese of the American Episcopal Church in California who happens to be a lesbian. There’s maturity for you. Faithful, seriously worshipping Christian folk have made a free decision in an open election that the best candidate for the job is a woman, who has shown by her decisions in life that fidelity, love and honesty are demanded by her practice of the Christian gospel.

These Californian Anglicans are grown-up enough to believe that it is entirely irrelevant that such fidelity, love and honesty are expressed in a same-sex relationship rather than a heterosexual one. Perhaps they have come to the conclusion that it would be a strange sort of supreme being who cared that much for a particular configuration of genitalia in her servants.

The Episcopal Church of the United States of America has been subjected to continuous abuse and carping from fellow Anglicans, attempted poaching of its churches by dissidents and demands that it curb its understanding of love and sexuality to fit in with the sexual mores of an entirely different society. So American Anglicans have decided that enough is enough: that they should just get on with being Anglicans and elect the best person for the job.

It would be nice if the election of bishops in the Church of England were that democratic and so effectively took into consideration the wishes of all the diocesan faithful. That’s a job to be tackled in Lambeth Palace once the mince pies have gone down and the archiepiscopal sherry decanter put back in the sideboard.

Meanwhile, I hope that you may rejoice at Christmas in this multiform church over which you so graciously and thoughtfully preside – give a welcome to the continuing unobtrusive and untrumpeted trickle of converts, not least from your sister church of Rome, join in the worship at one of your cathedrals, so packed to the gills, so well cared for and cherished as never before in their history, and enjoy the heritage of beautiful music that is one of the treasures of Anglicanism.

The Christmas story may be expressed in biblical forms that are not very good history and which some of your congregations may find difficult to take literally, but Christmas music can sweep past the puzzles of words to celebrate a new human life, weak, vulnerable and humble, which is glorified precisely for that. You will know the saying of Thomas Aquinas, which a wise old Dominican friar once quoted to me over a great deal of Irish whiskey, that God is not the answer, he is the question. As long as your church, and all other churches, go on asking the question, they will never die.

Diarmaid

Diarmaid MacCulloch is professor of the history of the church at Oxford University. His latest book is A History of Christianity: the First Three Thousand years (Allen Lane). His BBC4 television series on the same subject ended last week.