Skip to main content

Verified by Psychology Today

How People Become Atheists

Testing three theories of religious non-belief.

Key points

  • Religious belief appears to be nearly universal in humans.
  • If religion is universal, the challenge is explaining why about a quarter of people are atheists.
  • Some people reject their religious beliefs in adulthood, but most atheists were raised that way.

Religion is a human universal. Every society that has ever existed has had some form of organized religion that has dominated its culture and often its government as well. For this reason, many psychologists believe we have an innate tendency toward religious belief.

And yet, in every society, there have also been those who have rejected the religious teachings of their upbringing. Sometimes they’re vocal about their disbelief, and other times they’re prudently quiet to avoid ostracism or worse. In recent years, it’s been estimated that up to a quarter of the world’s population is atheist.

If religiosity—the tendency toward religious belief of some sort—is innate, as many psychologists have speculated, then how can we account for such a large number of non-believers? This is the question that British psychologist Will Gervais and his colleagues explored in a study they recently published in the journal Social Psychological and Personality Science .

Why Is Religion Nearly Universal?

According to Gervais and colleagues, there are three major theories explaining the seeming universality of religious belief. Each of these also has an account for how some people become atheists.

Secularization theory proposes that religion is a product of cultural practices and transmission. According to this view, religion arose to serve new social needs as humans developed civilization. For instance, it helped enforce morality by inventing ever-watching gods that punished misbehavior in the next life if not this one. It also lent legitimacy to the government through divine sanction. Finally, it provided a means of assuaging existential concerns of the common people—that is, the worries we all have about the health and happiness of ourselves and our loved ones. It’s comforting to know that a god is looking after our best interests.

Secularization theory also formulates a prediction about how people become atheists by examining the so-called “post-Christian” trend of Western Europe since the last half of the twentieth century. As these countries have developed robust social safety nets, universal health care, and a stable middle class, religious attendance and affiliation have dropped precipitously. According to this view, a government that provides for the good of the people needs no divine sanction. And because the people no longer have existential concerns, they have no need for religion either.

Cognitive byproduct theory contends that religion arose from innate thought processes that emerged to serve other functions. Humans are very good at intuiting the thoughts and emotions of others, and it’s this “mind-reading” ability that makes us so successful as a cooperative social species. But this ability is “hyperactive,” leading us to also “read the minds” of inanimate objects or hypothetical unseen actors.

By this account, any self-reports of atheism only go “skin deep,” in that non-believers would have to actively suppress their innate religious feelings at all times. As is often said during war, “There are no atheists in the foxholes.” Such an attitude is based on the assumption that religiosity is innate.

Cognitive byproduct theory predicts that some people become atheists because they have strong analytical thinking skills, which they use to critically evaluate their religious beliefs.

Dual inheritance theory maintains that religious belief comes from a combination of genetic and cultural influences, hence the name. According to this view, we may have an innate tendency toward religious belief of some sort, but specific beliefs have to be inculcated during early childhood. This theory accounts for both the near universality of religion as well as the great variety of religious experiences we observe across cultures.

While dual inheritance theory recognizes the existence of innate religious intuitions, it also maintains that those intuitions need to be triggered by actual religious experiences. Thus, it proposes that people become atheists when they aren’t exposed to religious beliefs or practices as children.

If Religion Is Universal, Why Are There Atheists?

To test which theory best predicts how people become atheists, Gervais and colleagues collected data from over 1400 adults who composed a representative sample of the American population. These participants responded to questions intended to measure their degree of religious belief as well as the various proposed pathways to religious disbelief. These included feelings of existential security (secularization theory), analytical thinking ability (cognitive byproduct theory), and exposure to religious practices in childhood (dual inheritance theory).

The results showed that only one of the three proposed pathways strongly predicted atheism. Almost all of the self-identified atheists in this sample indicated that they had grown up in a home without religion.

In hindsight, this finding is unsurprising. After all, Catholics are fond of saying that if they have a child till seven, they have him for life. And while it’s not uncommon for people to switch from their childhood religion to a different faith in adulthood, it’s rare indeed for a person raised without religion to adopt one later in life.

Those who gave up their religion later in life invariably showed strong analytical thinking skills. Nevertheless, plenty of religious people displayed this ability as well. In other words, just because you’re good at thinking logically, this doesn’t mean you’ll necessarily abandon your religious beliefs.

Most surprising to the researchers was that they found no support for secularization theory. The post-Christian tendency in Western Europe has long been held up as a model for how not just individuals but entire societies can become atheist. But the data from this study suggest that the secularization process may be more complex than originally thought.

A Two-Step Process for Losing Your Faith

Gervais and colleagues propose a two-step model in the case of Western Europe. In the devastation that followed World War II, the post-war generation lost faith in the legitimacy of the Church as the defender of morality and the protector of the people. Since they stopped actively practicing their faith, their children grew up without religion and became atheists, just as the dual-inheritance model predicts.

I suspect there’s another reason why this particular study failed to find support for secularization theory. The theory contends that the purpose of religion is to assuage existential worries, but when the government provides womb-to-tomb social safety nets, religion is no longer needed.

All respondents in this study were Americans. In the United States, social security systems are weak, and universal healthcare is nonexistent. Virtually all Americans, regardless of their income, worry about losing their health insurance if they lose their jobs, and they worry about losing their homes and life savings if they have a serious health issue. In other words, Americans have faith in their religion because they have no faith in their government to take care of them.

In sum, humans may have an innate tendency toward religion, but this doesn’t mean that people will develop religious beliefs on their own if not exposed to them in childhood. Religion provides comfort for people in an uncertain and frightening world, and yet we also see that when the government provides for the welfare of the people, they no longer need religion. Given the track record in Western Europe over the last half-century, it’s clear that governments can placate the existential concerns of the masses far more effectively than the Church ever did.


Gervais, W. M., Najle, M. B., & Caluori, N. (2021). The origins of religious disbelief: A dual inheritance approach. Social Psychological and Personality Science. Advance online publication. DOI: 10.1177/1948550621994001