I was born and raised in France, and while I live and teach in the United States these days, I go back to France and visit other West European countries at civilized intervals. The intervals are far enough apart to offer a perspective one cannot readily get from being always there, but no so far that the thread of logic in observation is broken. And what strikes me ever more strongly every time I cross the pond back to the Old World is how what started as mostly environmental common sense about forty years ago has slowly morphed into a religious creed, replete with the usual behavioral accoutrements.

It only takes a cursory look at the sexual revolution of the past half-century to see how fluid morality can be. Consider homosexuality. Within a single generation (in the West), a pervasively homophobic culture became not just tolerant but protective of same-sex relations. At no point did homosexuality escape the grip of moral scrutiny; it is rather the parameters of what passes for deviancy that changed. Moral violation demands a free will, negated by a simple cultural subterfuge: “gayness,” presumed to be a condition of being, eliminates the element of choice in homosexuality. A complete moral reversal followed. Hostile attitudes that were once a norm became a reviled mark of bigotry, and what was once deviant became normal, before it became moral through (same-sex) marriage.

Such shifts expose a morality that is not fixated on natural boundaries between right and wrong, but is driven to define and enforce norms, whatever they may be, based on what amounts to an ahistorical form of denatured Rawlsianism. Human societies are powerful moral machines that need to be fed demons to eradicate. The sexual revolution, by downgrading concerns about lewdness, created a space for other issues to enter the Western moral landscape—issues like the environment. The 1960s witnessed both a spike in sexual freedom—contraception and abortion were becoming available across the West—and a simultaneous embrace of nature and the simple life in opposition to post-industrial consumerism. (This was nothing entirely new; similar back-to-the-earth impulses had sprung from the Industrial Revolution, like the early 20^th-century “arts and crafts” movement that recognized and elevated the sensibilities of children.) By the late 1970s, hippie naturalism had morphed into environmentalism, a political and moral cause that rapidly crystallized into an ideology, then a dogma, and eventually a full-fledged religion.

The entry point of environmentalism in human morality has been an archetypal millenarian prophecy, one where humans are on the verge of destruction because of their sins, and where only a radical modification of their behavior could save them. There were precursor narratives in the 1970s (the nuclear Armageddon that would follow the expansion of nuclear power plants) and 1980s (mass irradiation from the erosion of the ozone layer, not to mention the specter of “global winter”), but it is global warming that has stuck. Being anthropogenic, global warming has the element of behavioral choice necessary to be a moral issue; being apocalyptic, it has the gravitas to impress. Global warming is diffuse and slow, imperceptible for the most part; yet its agency can be imagined behind any natural catastrophe, floods or draughts, hurricanes or blizzards. It is the kind of familiar devil upon which theologies rest.

Tellingly, environmentalism muted the demographic alarms that came from Malthus in the late 19^th century, later echoed by Club of Rome intellectuals in the 1970s. Around that time, concerns about an imbalance between the carrying capacity of the environment and world’s growing population inspired one-child policies and sterilization campaigns in populous states like India and China. But environmentalism, as a true moral crusade, has switched the focus from numbers to behavior. It is preparing to accommodate a human biomass of 10 billion specimens—projected circa 2050—by forcing them to make space for each other, and for the rest of nature. Like all religions, environmentalism has a way of embracing pain, and the future it promises to humans is one of high density, greater discomfort, and endless limitations.

Environmentalism has scriptures and prophets, too. The scientific data is massive and abstruse. Reports from the Intergovernmental Panel on Climate Change log thousands of pages, and it is incumbent on the priests of the environmental church to interpret the texts for the general public. Models are simplified and dramatized to impress the audience and elicit behavioral change. The priests acknowledge among themselves that they are doing this, just like the priests of old did. The saving of souls seems to require a fair bit of paternalism.

For the masses, environmentalism translates into rituals and prohibitions. The daily routines of recycling, often poorly understood and poorly executed, are acts of faith, first-order rituals on the road to redemption. Magic cannot be far behind. For example, there are economic reasons to oppose GMOs developed by big agri-business corporations, but notions that they are poisonous are squarely in the domain of superstition. Moral compulsions to eat local and “organic,” to hike and bike, are reminiscent of medieval holidays and pilgrimages, with its fasts and endless treks. However contrived, relative deprivation—the renunciation and denunciation of excess, the endurance of pain—has always appealed to the penitent. Salvation is simultaneously social and personal: Deprivation is supposed to bring better health and longevity, all the while contributing to the common good.

Environmentalism has already taken fundamentalist turns. Some have elevated the preservation of biodiversity to a sacred cause, even though there is no point in time that defines a “pristine” or desirable distribution of life forms on earth. Species evolve, spread, or disappear; environments change. This has always been happening. It is therefore not a violation of the deity-as-nature for evolution to let a species’ biomass run wild, as humans have since the 19^th century, even if it is to eventually crash under the pressure of its own growth. Some environmental causes, too, come across as extravagant, putting principle above practicality, like the ambitions of some global cities to achieve “zero waste.” This bears quasi-messianic overtones.

Laws and bureaucracies have been created to uphold the cause of the environment, adding institutional expansionary dynamics to moral creep. Regulators and enforcers, to justify their jobs, naturally create more regulations. The cult of the Earth (capitalized, of course) is deeply imprinted on children from their pre-K years, without reservation or qualification, and it becomes foundational to their conception of the sacred as with the Gods and Nations of the past. An economy of green moralism has emerged, with expensive recycling schemes, eco-friendly manufacturing, and all sorts of eco-taxes. Payments to offset carbon footprints resemble medieval indulgences paid to the church as atonement. Vigilantism has sprouted around the recycling campaign, with neighbors denouncing neighbors for their waste-related deviancy. Torquemada is looking up from the depths of Hell, and smiling.

Predictably, environmentalism has thrived among populations that are most distant from traditional religions and morality, like American liberals and the European Left. Greater tolerance in moral dimensions like sexuality is balanced by a more consuming observance of environmental rituals, and a more aggressive approach to deviancy. Issues change, but aggregate morality is constant.

There are some differences on the shores of the pond. In the United States, a more conservative nation where religious practice endures, full-blown environmentalism remains limited to specific socio-cultural milieus, such as San Francisco. The environmentalist call is most ubiquitous in the wealthy, socially liberal countries of northern Europe. Populations there have the means and leisure to adopt environmentalist practices that become central to their morality, and even to their identity. Green parties do well enough in general elections to leverage their seats into policies. Environmentalism is spreading across the landscape. Wind turbines, erected to the frightening gods of climate change, tear through the bucolic countryside like the steeples of medieval cathedrals. Urban tramways are built at great cost to turn cities into temples of the green dogma. Environmentalism is a way of life, a guiding church that influences what people eat, how they live their lives, how they behave socially.

There is no denying anthropogenic climate change; after all, the data make clear that it really started in earnest about 10,000 years ago with the beginnings of agriculture. We should not be indifferent toward pollution and littering, noxious chemicals and radiation, endemic smog and traffic gridlock. And nature’s beauty is unquestionable. But it is disconcerting that the challenges associated with high population density and high consumption—which are real and affect everyone—are being tackled not from a reasoned cost-benefit analysis, but from the expansion of what is essentially a religious emotion.

Policies should be holistic. Debates should involve all and balance contradictory objectives: speed and safety, security and freedom, development and preservation. But in reality, a few activists are conquering the minds of the majority, at least in Europe. Sensible arguments about the side effects of particular behaviors are invariably amplified by a good dose of distortive doom. Common sense then surrenders to a morality that, by nature, is prone to hyperbole and excess, to turning good intentions into restrictions and intimidation.

This dynamic is actually a window on the evolution of sexual morality, hundreds of years ago. It is easy to see how sexual restraint can be socially beneficial, but too much of a good thing can turn into puritanical intolerance. If people today think that past norms of sexual repression were absurd and oppressive, they should at least entertain the possibility that modern attitudes toward protecting the environment are quickly becoming no less questionable, and hypocritical.

The United States is still far behind Europe in its environmentalist worship, but it is precisely this striking contrast that shows how rapidly and deeply the cult has and can spread. Humanity is once again living in a millenarian moment, and it is essential to speak up for critical thinking against creeping extremism.