In the spirit of honesty and candour that Julian Baggini has recently enjoined on all parties in his Heathen's progress, I feel it is incumbent on me to admit the following: the latest instalment of the annual British Social Attitudes (BSA) survey reads like a nightmare for anyone (like me) who is concerned about the future of the Church of England. Chapter 12 of BSA 28, published last week, feels more like an Anglican epitaph than a chapter of social analysis.

The research is, in fact, an update of the more substantial treatment of religion published by BSA two years ago and the theme is a similar one. Since 1983, the number of people self-affiliating to the Church of England has halved, most going off to the no-religion camp, which has increased from 31% to 50%.

The reason for this change is predominantly down to what is known as the cohort effect, when younger generations (in this case less religious ones) replace older (more religious) ones. The fact that the trend is based on cohort, rather than life cycle (ie what stage in life you are), suggests that it is liable to be a long-term one.

There are, of course, attenuating factors, as there are in any social research. "Non-religious" does not mean atheist, still less hostile. Other Christian denominations have held reasonably steady over the past 27 years. And there is evidence that religiosity is a simply another victim of broader social trends, not least the public's general hostility towards joining big institutions. All of this is true and relevant, but it doesn't change the underlying story of the data: affiliation to the national church in England is, at present, on a downwards trajectory.

The fact that the decline in Anglicanism has mainly profited the non-religious section of the population invites further questions, with two particularly worthy of note.

The first relates to the need to understand non-religious moral universes. If half the population claims no religious affiliation, we need now to ask: to what creed or culture, if any, do they claim affiliation? How residual is the nation's Anglican culture within their ethical world views? Precisely how else do they inform those views? If there is a substantial population that no longer affiliates with any religious tradition, however faintly they may have once done so, it is necessary to understand where their ethical moorings extend. Airy claims about "reason" or "common human values" simply won't do anymore.

Heaven knows, religiously moored societies have proved fallible enough in the past. But at least they had some external moral standards to which they could be called to account. The absence of such lines in the sand augurs not so much moral freedom as moral relativism.

The second question relates to retention levels, ie the likelihood that you will remain affiliated to a certain group if you were brought up in it. For Anglicans and those of other Protestant traditions the figure is a mere 49%. The Catholic church fares a little better, with 62% of those brought up a Roman Catholic staying a Roman Catholic (although how seriously Roman Catholic is, of course, another matter). Better still are those brought up in non-Christian religions (unhelpfully not distinguished in the BSA chapter: it would be good to know how it differed from one minority religious group to another), 87% of whom remain in the faith.

But by far the most successful retention rates are in the "no religion" category. Nearly everyone – 94% to be precise – brought up without religious affiliation in Britain today stays without religious affiliation. Basically, if your parents bring you up outside a faith, you stay outside a faith. Who was it that said, give me the child, and I'll give you the man?

This is an extraordinary figure and apt to be interpreted in different ways. The irreligious will say that since people have no need of religious mumbo-jumbo, there is simply no reason why those brought up outside a religion should want to enter it. The religious will point instead to the fact that the non-too-subtle incredulity and contempt in which our culture holds serious religious commitment, will mean most young people are indoctrinated against it before they have a chance to consider it seriously.

It will take careful qualitative and quantitative research to adjudicate which of these positions is the more defensible. But I already have my suspicions.