Could Islam one day become the established church of Britain? Might English women adopt the headscarves and enveloping robes of their Asian sisters, as the call to prayer rises and falls across the slate roofs of rainswept industrial cities?
The idea is not as impossible, as bizarre or distant as you might think. An astonishing Channel 4 programme last week - The Last White Kids -- showed two English children who live in an entirely Muslim district becoming enthusiastic attenders at the local mosque, wrapping themselves in Islamic draperies and learning the Koran.
Amie Gallagher, nine, and her sister Ashlene, 12, are all-too-typical children of modern Britain in some ways, daughters of a single-parent household where the father is absent.
In Islam they seem to have found something that would otherwise be missing from their lives. At the mosque there is authority, certainty, even disciplined education in the Arabic language and the Koran.
This has happened because the Gallaghers are the only white family in a suburb otherwise completely dominated by Asian Muslims.
If they move away, as they may well do, then perhaps the two girls' attachment to the mosque will fail. Their brother, Jake, has not followed them down the Muslim path and has instead become even more defiantly English than he might otherwise have done.
But this strange little story contains a warning for Britain as a whole, as it careers ever more rapidly down the path of permissiveness which began so gently in the Sixties and now slopes ever more steeply downwards towards sexual chaos, drunkenness, family breakdown and the epidemic use of stupefying drugs.
Sooner or later, as in every other era of human history, there will be a revulsion against this licence, a desire to stop the waste, cruelty and misery which these things bring, especially to children.
Where will that revulsion come from? In the 18th and 19th Centuries it came from Christianity and the mighty but forgotten Temperance movements which reacted against the squalor and misery of Hogarth's Gin Lane, and whose effects we still just feel.
But Christianity shows little sign of doing the job a second time. Its leaders are more concerned about foreign conflict than about domestic misery, and more interested in the sexual tastes of bishops than in trying to regulate the confused sex lives of Britain's young.
The Christian churches have all but disappeared from the lives of the British people. The chapels of Wales are gaunt ruins, the great Roman Catholic churches of the industrial North West are often empty and derelict, the Anglicans scuttle about in their hallowed, lovely buildings like mice amid ancient ruins, rarely even beginning to fill spaces designed for multitudes.
The choirs and the bells gradually fall silent, the hymns are no longer sung and one by one the doors are locked and places which in some cases have seen worship for centuries become bare museums of a dead faith.
Few listen to what these churches say. They have become exclusive clubs, whose members celebrate bizarre rituals which are baffling to outsiders.
The Christian message is a difficult and complicated one, which if not learned in childhood is hard for adults to understand. The Christian ceremonies, viewed coldly by an outsider unschooled in 2,000 years of tradition, are positively peculiar. Why would anyone eat God?
When Christianity was part of our culture and its beliefs were handed down in homes and schools, its familiarity kept it strong. Everyone knew Bible stories, hymns and prayers. Now it is at least as alien to many young people as Islam, if not more so because it does not seem to be interested in them.
But Islam is interested in them. And Islam is growing. More and more British cities have seen the domes and minarets of smart, prominently positioned new mosques rising in their neighbourhoods.
A large and imposing Islamic centre is now nearing completion in Oxford, one of Christian England's holiest places. Imagine what would happen if Anglicans sought to build a Christian centre in Qom, Isfahan, Najaf or anywhere on the soil of Saudi Arabia, and wonder what Muslim leaders think of Christian feebleness on such matters.
Thanks to the immigration of recent decades, Britain has a young, energetic and swelling Muslim population which is increasingly assertive about its faith.
Official Islam may disapprove of such things but there have even been signs of the Muslim intolerance towards Christianity that is a nasty feature of so many Islamic societies.
In the Bradford suburb of Girlington, not far from where the Gallaghers live in Manningham, Asian youths tried to set fire to an Anglican church. Soon afterwards, a Brownie pack leader was attacked in a nearby street by young men who snarled 'Christian *****' at her.
An isolated and meaningless incident? You might hope so, but it would be unwise to be sure.
If you travel to these areas, you get the sense that Islam, one of the great forces of history, long ago defeated by the armies and navies of a mighty Christian Europe, is once again feeling its strength and finding that it has been able to penetrate what were once the most impregnable fortresses of its great rival.
Islam's appeal, wherever it has triumphed, has been in its simplicity. It requires submission to some basic, straightforward rules which are easily kept, and in return it offers that most wonderful and rare commodity, peace of mind. To modern Westerners, its attitude towards women seems incredibly backward and even hateful.
But as the reactions of Ashlene and Amie Gallagher show, its discipline, safety and certainties have an appeal for girls lost in the churning seas of permissiveness, whose own families have been weakened by the crumbling of the two-parent family, the absence of fathers and the impermanence of husbands, if there are husbands in the first place rather than boyfriends and ' babyfathers'.
And in most societies it is the women who sustain religions in the home and among children. In a country in the grip of unbelief, those with strong, clear convictions and an uncluttered message have a great advantage over those who offer nothing but choices to the perplexed and cannot seem to make up their minds about anything.
So if eventually Britain begins to sicken of strong lager, pools of vomit, Bacardi Breezers, bouncers looming on every High Street, the battlefields in the streets of many towns on Friday and Saturday nights, ecstasy tablets, cocaine, football-worship, pregnant 12-year-olds, morning-after pills and all that goes with them, is it possible that puritan Islam will be the cause that benefits?
If bureaucratic police and feeble justice continue to fail to suppress crime and disorder, will the savage but simple remedies of Sharia law begin to appeal to the British poor, who are already weary of seeing dishonesty triumph everywhere and lawless violence go unchecked?
Might Islam become respectable among the politically correct middle classes, in a way that Christianity never really can, because Christianity is always associated in this country with the conservative, imperial past?
You will already find plenty of bright young Muslims in our universities, many of whom are impressive and diligent students, and their influence is bound to increase as they move into the professions.
The idea of an Islamic Britain may seem highly unlikely now, amid what still seems to be more or less a Western, Christian society. We are used to thinking of Islam as a religion of backward regions, and of backward people.
But we should remember that Muslim armies came within inches of taking Vienna in 1683 and were only driven from Spain in 1492. In those days it was the Islamic world that was making the great scientific advances which we now assume are ours by right.
And is it any more unlikely than the things which have happened here in the past 40 years, during which a country of peaceful, self-restrained, lawful and rather prudish men and women has been transformed into the land of sex and swearing on TV, ladettes, semi-legal cannabis and armed police?
If we don't respect our own customs and religion, we may end up, as Ashlene and Amie Gallagher have done, respecting someone else's. Don't be surprised.