But here is the problem. If a person rejects that church affiliation, and abandons the religious community, how long can they maintain that solitary or non-affiliated religious practice before it dies altogether? Ten years? Thirty? And can that attenuated practice be passed on to the next generation? When does "no religious affiliation" transform into a simple "No religion at all, seriously, and I mean it"?

European evidence suggest that countries do indeed reach this point. A striking 2016 study showed only a third of Dutch people claiming any faith at all, with Christianity still the largest component, at 25 percent. That number was exactly paralleled by the quarter of the population who were outright atheists. Even the number who reported belief in any higher power, rather than a specific concept of God, is falling steadily. By 2017, 52 percent of British people reported having no religion, and the rate for people under 24 was 70 percent. The most significant growth was among those who accepted the label of "confident atheists."

Those figures were rather worse than the larger European norm, but the picture of European detachment from religion is common. Across the region the proportion of the religiously unaffiliated is an impressive 24 percent, outnumbering churchgoing Christians. Besides the Netherlands, the unaffiliated figure is highest in Belgium, Norway, and Sweden, at over 35 percent. The lowest figures were for Ireland, Portugal, and Austria, at 15 percent. Throughout the region the great majority of these unaffiliated--the Nones--had been baptized and raised Christian. Overwhelmingly those unaffiliated agreed with the statement that science made religion unnecessary for them.

Straightforward atheism has become a common creed, markedly so in some societies. In a recent survey, the proportion flatly asserting no belief in God was at its height in the Czech Republic (66 percent) and Sweden (60 percent), with high levels of disbelief in Belgium, the Netherlands, Norway, and Estonia. This trend is particularly pronounced in large cities. Berlin vaunts its role as the atheist capital of Europe, and 60 percent of residents claim no religion. In France, 11 percent of respondents accept God's existence absolutely while 45 percent are less certain and 37 percent are atheists.

Just to take two examples, if you go back to 1960, then both Belgium and the Netherlands were high on the list of the world's very religious societies, and Belgium was very Catholic indeed. Now look where they stand in the atheism stakes. They are also among the world's most systematically liberal societies in terms of legislation and policies that have been passed in the teeth of bitter opposition form the respective churches.

The drift away from religion is so advanced, and progressing so swiftly, that some scientific surveys project the extinction of faith of all kinds from several nations by the end of the present century. A study presented to the American Physical Society in 2011 predicted that by the end of the present century, nine nations would be entirely free of religion. Six of these were European, namely Austria, the Czech Republic, Finland, Ireland, the Netherlands, and Switzerland. Very striking here was the inclusion of nations like Austria and Ireland, where levels of faith are presently holding up relatively well. Actually the study suggested that other nations might well be following a like trajectory, but their official statistics did not permit the kind of analysis that would permit such conclusions. Not included in the list, therefore, was Great Britain, which commonly appears alongside the Netherlands in listings of the world's most secular societies. (The other three nations on the APS listing were all Anglophone members of the former British Empire, namely Australia, New Zealand, and Canada). Of course, any such long-term projections are tenuous, but the listing of countries is suggestive.

The decline of supernatural belief undoubtedly has occurred in much of the West, and faith continues to recede. As a character in one of Tom Stoppard's plays aptly remarked, "There is presumably a calendar date--a moment--when the onus of proof passed from the atheist to the believer, when, quite suddenly, secretly, the noes had it." We are now well past that point. But how much further will the process continue? Some very credible social scientists believe that recent trends herald the destruction of religion in any form we have known, if not the actual abolition of religious faith as such. In the short term, such analyses are chiefly based on European experience, but the long-term implications have global relevance.

One of the leading scholars on the religious implications of demographic change is David Voas, who declares unequivocally that

Religion is in decline across the Western world. Whether measured by belonging, believing, participation in services, or how important it is felt to be, religion is losing ground. Older generations die out and are replaced by less religious younger generations. Modernization has predictable and permanent effects, one of which I call the secular transition. . . . Certain major transformations--such as the industrial revolution or the demographic transition (the decline first in mortality and then in fertility)--occur exactly once in each society. These transitions are very difficult to undo. Back-tracking is exceptional and temporary: slavery isn't restored after it's been abolished, nor do women lose the vote once granted. A transition is permanent, not cyclical or recurring; once out, the toothpaste won't go back into the tube. Secularization is such a transition.

Voas is speaking broadly of a decline in actual belief, rather than just institutional structures. Callum Brown is still more explicit. As he writes, "The Western World is becoming atheist. In the space of three generations churchgoing and religious belief have become alien to millions. We are in the midst of one of humankind's great cultural changes."

Although these scholars are discussing the West, there is no intrinsic reason why the changes that have overtaken Western religion should not have their impact on a global scale and, ultimately, even in Africa. If such views are correct, then Christianity has a specific expiration date, to be followed after some delay by the other great faiths. At some not-too-distant point, perhaps in the mid-twenty-second century, God would become an extinct species.

In my recent book Fertility and Faith; The Demographic Revolution and the Transformation of World Religions, I suggested why we should take such views very seriously indeed, although my own conclusions were nothing like so pessimistic. But to return to a core question. At least for right now, we absolutely must not take "Nones" as synonymous with atheists, fine. But once they abandon religious affiliation, how long can those Nones retain any religious identity whatever? European examples suggest that it might not be more than a generation.

I'd worry.

Just to end with a quote I have always liked. In seventeenth century England, there was a then-famous playwright called Sir William Davenant (1605/6-1668), who was suspected of being an illegitimate son to Shakespeare. Davenant strongly encouraged the tale, and the possible connection, however badly that reflected on his mother. Looking at the desperate religious wars around him in that era, all the fanaticism and violence, one of his friends tells us that "His private opinion was that Religion at last, -- e.g. a hundred years hence, -- would come to settlement, and that in a kind of ingeniose Quakerisme." No more Catholics or Protestants (or Jews or Muslims), just a kind of peaceful ethical creed, devoid of sacraments or hierarchies, just waiting on the Inner Spirit. Love it or hate it, it was a fascinating prediction. And maybe an ideal creed for Nones.

My new Church of Ingenious Quakerism will go live shortly.

Philip Jenkins is a professor of history at Baylor University in the United States, and co-director for Baylor's Program on Historical Studies of Religion in the Institute for Studies of Religion. He is also the Edwin Erle Sparks Professor of Humanities Emeritus at Pennsylvania State University.