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Data from around the world indicate that religious belief is in decline. This trend began long before the internet and social media were invented. But it has accelerated and intensified dramatically since their arrival. According to sociologist Jean Twenge, between 2004 and 2016, religious belief among young adults “fell off a cliff.”

For a time, it was argued that the United States was a counterexample to worldwide secularization. Mixed findings made it difficult to disentangle what sociologists call cohort effects, in which belief decreases further with each successive generation, from age effects, such as the tendency for religious belief to decrease during adolescence and rise again after middle age, or period effects, such as a general dip in belief during the 1960s.

However, recent studies indicate not only that patterns of secularization in the United States are similar to those observed elsewhere but also that Gen Z is significantly less religious than any preceding generation.

Secularization is a complex process. It includes not only declining belief but also declining participation and observance. And it has many sources—economic, political, social and intellectual. Nevertheless, a key factor in the decline of religious belief among millennials and Gen Z seems to be what distinguishes them, as digital natives, from all previous generations: their use of internet and social media. Few studies have examined directly the effects of internet use on religious belief, but those that have indicate a negative correlation.* Viewed alongside evidence that the decline in religious belief accelerated at the same time that internet use increased, and that they did so most sharply among the generations that use it most, these data suggest strongly that the trends are related.

Does the internet, then, promote incredulity?

Perhaps that’s what we might have concluded if the internet and social media weren’t so effective at spreading beliefs of other kinds—from belief in conspiracy theories and fake news to increasingly polarized political opinions. In one recent survey, 29 percent of Americans expressed belief that a “deep state” was working against President Trump; 19 percent that the government was using chemicals to control the population; and as many as 9 percent subscribed to the QAnon-linked “Pizzagate” theory, which claimed that a Washington elite was running a pedophile sex-trafficking ring out of the basement of a D.C. pizzeria. Any thoughts that those subscribing to conspiracy theories believe in them with anything less than utter conviction were dispelled when insurrectionists, emboldened by a relentless #Stopthesteal campaign on social media, stormed the U.S. Capitol, intent on reversing the result of a democratic election.

But how can the internet be driving both these trends? How can it promote, at one and the same time, both credulity and incredulity?

What underlies both trends is a general crisis of credibility. Each new advance in communications technology opens up new possibilities for misrepresentation. In the age of “deepfake,” it is almost impossible for the untrained to distinguish fabricated documents, photos, and videos from genuine ones. Worse still, recent research indicates that fake stories travel six times faster and further on social media than do factual ones. The net effect is general pollution of the information environment, to which many respond in one of two ways. Some become generally distrustful, presuming all incoming information to be fake until proven credible. Others trust too much in the credibility of sources whose views echo their own. What these responses have in common is an evacuation of the middle ground between certainty and disbelief.

In other words, the internet influences not only what we believe but also how we believe. We are shifting from analog to digital not only in our modes of communication but also in our conceptions of what belief is and how it works. The idea of belief as a continuous variable measured in degrees of certainty is being replaced by the idea of belief as a binary function of zero or one, or “all in” versus “all out.”

This transformation is not necessarily a conscious one. I am not suggesting that people don’t recognize degrees of doubt or certainty when they encounter them. I am suggesting, instead, that the ways in which we interact with information online push us to reduce nuance and ambiguity when processing that information and to make quick judgements about whether to believe it or not. The key driver in this process is the sheer amount of incoming information, reliable and unreliable, that we have to process. Shortcuts are needed. And, over time, these shortcuts are affecting how we believe more generally.

A helpful analogy here is the difference between analog and digital sound. In his fascinating book, Ways of Hearing, musician Damon Krukowski notes that a key difference between the two kinds of sound concerns the ways each is engineered to distinguish signal from noise. In digital reproduction, everything deemed noise is eliminated entirely, leaving only signal. In analog reproduction, noise cannot be eliminated, only minimized, by foregrounding the signal and consigning noise to the background. However, one person’s noise is another person’s context—context that is lost in the move to digital.

To illustrate, Krukowski demonstrates how the digital microphone in the modern smartphone is much better than the analog one in old rotary phones at eliminating background noise but much worse at communicating emotion. Communicating emotion depends on things like distance from the receiver, sighs, pregnant silences, and shifts of tone that analog microphones pick up and transmit to the listener but that digital microphones and smartphone software eliminate as noise.

The intuitive filter systems we are developing to cope with the relentless flow of incoming information are transforming how we believe. To eliminate the noise of unreliable information, we are developing habits of skepticism and trust that, as a by-product, also eliminate the nuance of qualified belief and degrees of certainty.

Religious belief appears to be especially sensitive to this transformation. As people gravitate toward the opposed poles of fundamentalism and skepticism, many in the shrinking middle are becoming alienated by the excesses of one or other pole and seek solace in its opposite. For example, Twenge cites evidence that declining religious belief among contemporary adolescents is due in part to their association of religion with views they consider rigid and intolerant. Another recent study identified distrust of religious institutions as a significant factor in Gen Z’s unprecedentedly low levels of religious belief and practice. Gen Z participants in the study expressed distrust in many national and community institutions, but trusted religious institutions even less than they trusted banks, the medical system and public schools, and only slightly more than they trusted online and print media.

Secularization, however, also differs in some ways from the distrust we are seeing in areas other than religion. Distrust in politicians, governments, news sources, academics, and so on is analogous to distrust in religious traditions, institutions and clergy. But secularization involves, beyond this, declining belief in the existence of God. More relevant analogies here, therefore, may be beliefs in specific entities such as the Illuminati (a conspiracy-laden cabal of powerful individuals, alleged to control world affairs) or specific phenomena such as climate change (a well-substantiated but nevertheless much debated scientific finding). Such beliefs are based on testimony, and as such, depend on trusting the sources of that testimony. Except in cases of personal religious revelation, in which people believe they have experienced God directly, belief in God is similarly reliant on testimony. And it is here, on our trust in testimony, that the internet appears to have its dichotomizing effect.

Much commentary on the internet’s role in the rise of closed ideological systems likens them to new religions, suggesting that adherents of conspiracy theories and radical social movements believe and act with a certainty typical of religious believers. Assumptions like these are so widespread that they often slip unremarked into the design of social research. For example, a recent report by the consumer research company, Statista, titled “Belief and Conspiracy Theories in the U.S.,” opened with data on religious beliefs and ended with data on superstitions and conspiracy theories. This practice gives the impression that these different kinds of belief are actually pretty similar and can be organized hierarchically from less to more outlandish.

However, such impressions rest on a caricature of religious belief and misconceive how it functions in practice. Religious believers regularly experience doubts and readily quantify the degree to which they believe in various articles of faith when questioned in surveys. Moreover, recognition that a person’s religious belief waxes and wanes is by no means a modern innovation. Most, if not all, religious traditions address doubt explicitly in canonical texts, rituals, and liturgy. Indeed, a compelling philosophical case can be made that faith requires doubt. Where there is no doubt, there can be no faith, either; only certainty.

In the digital age, therefore, the greatest threat to religious belief might come not from atheism or skepticism but rather from its mischaracterization as just one more form of partisan certainty. Correspondingly, religion’s greatest contribution at this time might be to resist binary conceptions of belief and to model the humility that comes from keeping faith, and acting with conviction, in the face of doubt.

The internet is changing how we process information and trust the sources from which it comes. To cope with the relentless flow of incoming information, in which fake and real are increasingly indistinguishable, we are developing defaults of distrust and trust in which atheism and fundamentalism can flourish but other forms of religious belief are difficult to sustain. Those most affected by these developments are Gen Z, the smartphone generation.

But the challenges the internet poses to belief extend beyond Gen Z, and even beyond religion. Our capacity and motivation to assess the relative credibility of conflicting claims, or the trustworthiness of competing sources of information more generally, depends ultimately on our preserving analog forms of belief that leave room for nuance and uncertainty. A digital world with no room for analog faith is a world in which reasoned debate between people holding different beliefs is ultimately impossible.

Eli Gottlieb is a cognitive psychologist and advisor to government and nonprofit organizations on leadership and strategy. His research examines connections between cognition, identity, and culture.

*This sentence had incorrectly stated that there was a positive correlation. The studies indicate a negative correlation, meaning as internet usage goes up, religious belief goes down.