The claim is blunt, intentionally provocative, and for many, deeply offensive. Yet, the idea that religious belief is linked to lower intelligence is not merely an insult hurled in the heat of debate; it is a question that has been the subject of scientific inquiry for nearly a century. Research into the relationship between cognitive ability and faith began as early as the 1920s, and since then, a substantial body of evidence has accumulated, pointing toward a consistent and uncomfortable conclusion. This report will unpack what science actually says about this link, moving beyond a simple slur to a deeper understanding of the psychological, social, and evolutionary forces at play.

The central finding, confirmed across decades of research, is a statistically significant negative correlation between intelligence and religiosity. In simple terms, this means that, on average, individuals who score higher on standardized intelligence tests tend to report lower levels of religious belief. This is not a fringe idea from a single, biased study. The conclusion is built upon the most powerful tool in a scientist's statistical arsenal: the meta-analysis. A meta-analysis pools the data from dozens or even hundreds of individual studies to arrive at a more robust and reliable estimate of an effect.

Several landmark meta-analyses have solidified this finding. In 2013, a team of researchers led by Miron Zuckerman analyzed 63 studies and found a reliable negative relationship. Specifically, for college students and the general population, the average correlation (r) between intelligence and the strength of religious beliefs was between −.20 and −.25. In 2020, Zuckerman's team published an update, expanding their analysis to 83 studies. The results held firm, confirming the correlation in a similar range of −.20 to −.23 and demonstrating the durability of the finding over time. Most recently, a 2022 meta-analysis by Florian Dürlinger and Jakob Pietschnig examined 105 studies with over 200,000 total participants. Using a sophisticated "multiverse" approach that tested 192 different reasonable ways of analyzing the data, they found a small but robust negative correlation of r=−.14, concluding that the link is "virtually ubiquitous" and that 70.4% of all possible analyses yielded a significant negative result.

The existence of this negative correlation, therefore, is not seriously in dispute within the scientific community. The far more interesting question—and the focus of this report—is why it exists. The answer takes us deep into the architecture of the human mind, revealing a fundamental tension between two different ways of thinking. We will explore the leading psychological, social, and evolutionary theories that explain this phenomenon, and in doing so, we will ultimately be forced to question whether "dumbness" is the right word at all.

To understand the link between intelligence and religiosity, it is first necessary to move past the loaded term "dumbness" and define intelligence as it is used in this field of research. It is not merely about "book learning" or possessing a wealth of facts. Rather, intelligence, often measured as an Intelligence Quotient (IQ), is defined by psychologists as a "very general mental capability" that involves the ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, and learn quickly from experience. It reflects a broad and deep capacity for making sense of our surroundings and figuring out what to do. This definition is crucial because it shifts the focus from what a person knows to how a person thinks.

This "how" is at the heart of one of the most influential models in modern psychology: dual-process theory, popularized by Nobel laureate Daniel Kahneman. This theory posits that our minds operate using two distinct systems:

• System 1 (The Intuitive Soul): This system is fast, automatic, effortless, and emotional. It operates on heuristics—mental shortcuts—and produces the gut feelings, immediate impressions, and intuitive judgments that guide most of our daily lives. From a cognitive science perspective, religious belief is often seen as a product of this system. Beliefs in gods, spirits, and an afterlife can feel "naturally" true, arising from powerful intuitions that do not require slow, effortful deliberation.

• System 2 (The Analytic Mind): This system is the opposite of System 1. It is slow, conscious, effortful, and logical. Its job is to engage in the complex computations, deliberate reasoning, and careful analysis that System 1 cannot handle. System 2 is what allows us to solve a difficult math problem, weigh the pros and cons of a major life decision, and, critically, to question and override the intuitive outputs of System 1. Engaging System 2 is mentally taxing, which is why we often rely on the "lazy" path of least resistance offered by System 1.

The tension between these two systems can be measured using tools like the Cognitive Reflection Test (CRT). The CRT presents simple-looking problems that have an obvious but incorrect intuitive answer. To arrive at the correct solution, one must engage System 2 to suppress the initial impulse and think more deeply. A classic example is: "A bat and a ball cost $1.10 in total. The bat costs $1.00 more than the ball. How much does the ball cost?" The intuitive System 1 answer that leaps to mind is 10 cents. The correct answer, which requires a moment of System 2 analysis, is 5 cents.

This brings us to the core of the psychological explanation for the intelligence-religiosity link. The data reveals a clear chain of connections:

1. Individuals with higher IQ scores tend to perform better on the CRT, indicating a greater propensity to engage in analytic, reflective thinking.

2. Individuals who perform better on the CRT, in turn, tend to report lower levels of religious belief.

3. Most importantly, the 2020 Zuckerman meta-analysis found that this analytic cognitive style partially mediates the relationship between intelligence and religiosity.

This mediation finding is profound. It suggests that the reason higher intelligence is linked to lower religiosity is not simply because "smart people know more facts." Instead, a primary mechanism is that higher intelligence is associated with a cognitive style—a greater tendency to use the analytical, questioning, and effortful processes of System 2. This analytic style then scrutinizes and often overrides the intuitive, System 1-generated beliefs that form the foundation of much religious faith.

This reframes the entire debate. The connection is not about a defect or a lack of capacity, but a difference in cognitive preference. Some research suggests that the performance gap between believers and non-believers is largest on tasks specifically designed to create maximum conflict between an intuitive response and a logical one. This indicates that the key difference may lie in the ability or willingness to inhibit an intuitive response when it clashes with logic. From this perspective, religious belief can be seen as the cognitive "default setting" for the human brain, a path of least resistance that feels natural and right. Disbelief, in contrast, is the product of an effortful cognitive override, a process that individuals with higher analytic intelligence are more likely to engage in. Thus, "dumbness" is a crude and inaccurate misnomer for what is actually a preference for a more intuitive mode of thought.

Beyond cognitive styles, another powerful theory explains the link between intelligence and religiosity by examining the fundamental human needs that religion fulfills. The "Functional Equivalence Hypothesis" posits that intelligence can provide alternative, non-supernatural pathways to satisfying some of the same core psychological needs that have traditionally drawn people to faith. If a person's life already provides them with a sense of control, purpose, and security, the "product" that religion offers may simply be less necessary. This theory breaks down into several key domains where intelligence can serve as a substitute for religion.

Life is unpredictable and often chaotic. A primary function of many religions is to provide a sense of control in the face of this uncertainty. The belief that a benevolent, omnipotent God has a plan for the world and for one's life provides a powerful sense of external control, offering comfort and predictability when personal control feels threatened. It suggests that even when things seem random or unjust, there is an underlying order to the universe.

Intelligence, on the other hand, fosters a sense of personal control. The ability to reason, plan, solve complex problems, and comprehend one's surroundings gives individuals a stronger feeling of agency and self-efficacy—the belief that they can shape their own outcomes. Research shows a positive correlation between intelligence and a belief in personal control. More intelligent people, by virtue of their enhanced problem-solving capabilities, may feel more equipped to manage life's challenges on their own, thereby reducing their psychological need for the compensatory control offered by a divine overseer.

Religions provide robust frameworks for self-regulation. They offer clear moral codes, prescribe rituals that instill discipline, and hold out the promise of long-term rewards (e.g., salvation, a favorable afterlife) for forgoing short-term temptations. This external scaffolding can be a powerful tool for promoting self-control and guiding behavior toward pro-social and long-term goals.

Here again, intelligence appears to serve a parallel function. Higher cognitive ability is directly linked to better self-regulation and a lower "delay discounting," which is the tendency to prefer smaller, immediate rewards over larger, delayed ones. A meta-analysis found a mean correlation of r=−.23 between intelligence and delay discounting, indicating that more intelligent people are significantly better at delaying gratification. This enhanced capacity for self-control, likely rooted in superior executive functions like working memory, means that more intelligent individuals may have less need for the external rules and incentives that religion provides to regulate their behavior. They are, in effect, better equipped to be their own moral-behavioral managers.

The need to maintain a positive view of oneself is a fundamental human motivation. Religion can be a powerful source of self-esteem. Belonging to a special community, having a personal relationship with a divine being, and believing one is part of a grand cosmic purpose can all enhance an individual's sense of self-worth.

Intelligence can also be a potent source of self-enhancement. While the correlation with self-esteem is modest, it is consistently positive. More significantly, the academic, professional, and personal achievements that are often associated with higher intelligence can serve as a powerful foundation for a positive self-concept. An individual who derives a strong sense of competence and value from their own abilities and accomplishments may have less of a psychological need for the external validation and self-enhancement that religious belief can provide.

Humans are social creatures with a deep-seated need for secure connections. For many believers, God functions as an ultimate attachment figure—a constant source of love, security, and comfort who provides a refuge from loneliness and distress, especially in times of loss or threat.

While intelligence does not directly create relationships, it has an indirect effect on the stability of human attachments. Research shows that more intelligent people are more likely to get married and less likely to get divorced. This may be because they are better at long-term planning, act less impulsively, and are more adaptable to the challenges of a relationship. By fostering the conditions for more stable and lasting human bonds, intelligence may reduce the need to seek attachment and security from a supernatural source.

Taken together, these four functions paint a compelling picture. They suggest that the lower religiosity observed among more intelligent people may not always be the result of a deliberate philosophical rejection of doctrine. Instead, it can be seen as a psychological consequence of self-sufficiency. If one's cognitive toolkit already provides a strong sense of control, self-discipline, self-worth, and secure human connections, the psychological appeal of what religion offers is naturally diminished.

Beyond individual psychology, two broader theories—one social and one evolutionary—offer further insight into why higher intelligence is linked with lower religiosity. These explanations situate the phenomenon within the larger contexts of social dynamics and the deep history of human cognitive evolution.

The first theory is straightforward: in most societies throughout history, religious belief has been the established norm. It is the default social position, reinforced by family, community, and culture. To be non-religious, therefore, is often an act of nonconformity—a willingness to resist prevailing dogma and stand apart from the group.

The evidence suggests that more intelligent individuals are, on average, less susceptible to social pressure and more likely to be nonconformists. A meta-analysis of studies on conformity and persuasion found that more intelligent people are more resistant to having their views changed. This may be because their greater cognitive abilities allow them to more critically evaluate arguments and identify flaws in dogma. Furthermore, their self-perceived uniqueness might make them more comfortable with the social isolation that can sometimes accompany dissent. In a world where belief is the norm, the intellectual confidence and independent mindset associated with higher intelligence may be necessary prerequisites for rejecting the consensus view.

It is important to note, however, that this explanation is highly dependent on social context. In a pervasively atheistic society, such as some former communist states, the act of nonconformity might be to embrace religion. This caveat highlights that the link is not just about intelligence, but about the interaction between intelligence and the dominant cultural environment.

A more fundamental explanation comes from the field of evolutionary psychology, which seeks to understand the mind's structure in light of our species' evolutionary past. One of the most influential theories in this field is that of cognitive anthropologist Pascal Boyer, author of Religion Explained. Boyer argues that religion is not a direct adaptation that was selected for by evolution. Instead, he proposes that religion is a "spandrel"—an evolutionary byproduct of other cognitive faculties that were adaptive.

According to this view, the human brain comes equipped with several "inference systems" that evolved to solve problems of survival and reproduction. These systems operate automatically and intuitively (as System 1 processes) and, as a side effect, make our minds highly receptive to supernatural concepts. Key systems include:

• Agency Detection: Our brains are wired with a Hyperactive Agency Detection Device (HADD). We evolved to assume that ambiguous events—a rustle in the grass, a shadow in the dark—are caused by an intentional agent (e.g., a predator or an enemy) rather than by random chance (e.g., the wind). Erring on the side of caution was adaptive. A major byproduct of this overactive system is the tendency to infer the presence of unseen agents, such as spirits, ghosts, and gods, behind natural phenomena.

• Theory of Mind: We possess a sophisticated ability to attribute mental states—beliefs, desires, intentions—to other people. This is essential for social interaction. It is a very small cognitive leap to apply this same system to the unseen agents we detect, imagining them to have minds, plans, and desires of their own.

• Minimally Counterintuitive (MCI) Concepts: Boyer's research suggests that religious concepts are so memorable and transmissible because they hit a cognitive "sweet spot." They are not completely bizarre, but they violate one or two of our basic, intuitive expectations about the world. A talking snake, a person who can walk on water, or a statue that weeps are MCI concepts. They are grounded enough in reality to be understood, but strange enough to be attention-grabbing and memorable, making them perfect fodder for cultural transmission.

This evolutionary framework connects directly back to the dual-process model of the mind. If religious beliefs are the natural byproducts of these fast, intuitive, and automatic cognitive systems, then they represent a kind of cognitive illusion. Our brains are naturally susceptible to them. From this perspective, higher intelligence—and the associated propensity for slow, analytic System 2 thinking—is the cognitive tool that allows an individual to step back, scrutinize these intuitive outputs, question their validity, and ultimately reject them as compelling but not necessarily true. The negative correlation between intelligence and religiosity, then, can be interpreted as a measure of how effectively different individuals deploy analytical reasoning to overcome a natural, evolved bias toward supernaturalism.

Thus far, this report has laid out the primary scientific evidence and theories that explain why, on average, higher intelligence is associated with lower religiosity. The data is robust, and the psychological mechanisms are plausible. However, to stop here would be to present an incomplete and misleading picture. The reality is far more complex and nuanced. A truly expert understanding requires acknowledging the significant limitations of this research and considering evidence that directly challenges the simple "dumb God" hypothesis.

The first and most important caveat is that while the negative correlation between IQ and religiosity is statistically significant, its effect size is small. A correlation of r≈−0.20 means that intelligence explains only about 4% (r2) of the variance in religious belief. This means that 96% of what makes a person religious or not is determined by other factors. Personality traits (especially Openness to Experience), upbringing, culture, education, economic conditions, and personal experiences are all part of a complex web of influences that are likely far more powerful than cognitive ability alone.

Because the effect is small, using an individual's IQ to predict their faith is a fool's errand. The researchers who conduct these studies are the first to issue this caution. As Miron Zuckerman stated, it is "truly the wrong message to take from here that if I believe in God I must be stupid," warning that he would lose a lot of money betting on such a premise. The world is full of brilliant scientists who are devoutly religious and people of modest cognitive ability who are staunch atheists. The correlation describes a faint trend across a large population; it is not a deterministic rule for individuals. The link is a real phenomenon that demands explanation, but it is not a hammer with which to bludgeon believers.

A second major limitation is the cultural bias inherent in the research. The vast majority of studies included in the major meta-analyses were conducted in Western nations—primarily the United States and Europe—with populations that are predominantly Christian or have been shaped by a Christian cultural heritage. This severely limits the generalizability of the findings.

The negative correlation may be specific to the particularities of Abrahamic monotheism, with its concept of a single, omniscient, omnipotent, and often paradoxical God. The intellectual challenges and perceived irrationalities associated with this specific theological framework might be what drives the negative relationship with analytic intelligence. The findings may not apply at all to Eastern religions like Buddhism or Hinduism, or to various polytheistic and animistic traditions, which have vastly different conceptions of divinity, the self, and the cosmos.

Indeed, some cross-cultural studies hint at a different story. Research on Muslims in Indonesia and Mormons in the United States has, at times, found a positive relationship between education or religiosity and certain cognitive measures. This suggests that the relationship is not universal but is shaped by the specific doctrines of the religion in question and the cultural context in which it is practiced. The current body of evidence tells us something about the relationship between intelligence and religion in the modern West, but it may tell us very little about the relationship for humanity as a whole.

Perhaps the most profound challenge to the "dumbness" narrative comes from questioning the very definition of intelligence itself. IQ tests are designed to measure a specific type of intelligence: analytical and logical-reasoning ability. But many psychologists argue that this is a narrow and incomplete view of human cognitive capacity. By focusing solely on IQ, we may be missing other forms of intelligence where the relationship with religiosity is not negative, but positive.

• Emotional Intelligence (EI): Often abbreviated as EQ, emotional intelligence is broadly defined as the ability to perceive, understand, manage, and utilize one's own and others' emotions effectively. While IQ is about cold cognition, EI is about the wisdom of the heart. Research into its relationship with religiosity reveals a complex but often positive picture. Several studies have found that religion can provide powerful frameworks and practices—such as forgiveness, compassion, and mindfulness—that help individuals regulate their emotions. A systematic review found that religiosity was generally linked to more adaptive emotion regulation strategies. Some studies add another layer of nuance, finding that an intrinsic religious orientation (where faith is an end in itself) is positively correlated with EI, while an extrinsic orientation (where faith is a means to social ends) is negatively correlated. This suggests that a sincere, internalized faith may actually enhance a person's emotional skills.

• Spiritual Intelligence (SI): A more recent but growing concept is that of spiritual intelligence (SQ). While definitions vary, SI generally refers to the ability to act with wisdom and compassion, to access higher meanings and values, to find a sense of purpose, and to embed these principles into one's life. It includes capacities like humility, the ability to reframe adversity positively, and a sense of vocation or calling to serve something larger than oneself. By its very definition, SI encompasses the core goals of many religious and spiritual traditions. These practices are, in essence, training programs for developing spiritual intelligence. Unsurprisingly, research has begun to show positive links between spirituality and social intelligence—the ability to understand and navigate social situations effectively.

This leads to a central paradox. While one form of intelligence (analytic IQ) shows a modest negative correlation with religiosity, other valid and important forms of intelligence (emotional and spiritual) may be positively correlated with it. The answer to the question "Are religious people less intelligent?" depends entirely on which kind of intelligence one chooses to measure. To focus only on IQ is to ignore the domains where faith may act not as an inhibitor of intelligence, but as a catalyst for it.

We began with a deliberately provocative question: Does being dumb make you believe in God? After a thorough examination of nearly a century of scientific research, the answer is a definitive, if complex, no. The word "dumbness" is a crude and misleading label for what is actually a fascinating and nuanced aspect of human psychology.

The evidence is clear and robust: there is a small but consistent negative correlation between analytical intelligence (as measured by IQ tests) and religious belief, at least in Western societies. The most compelling explanations for this link are not about a defect in believers, but about the very architecture of the human mind. Religious concepts appear to be a natural byproduct of our fast, intuitive cognitive systems—our mental "default setting." Higher analytical intelligence provides the cognitive tools and the motivation to engage in the slow, effortful thinking required to question and override these powerful intuitions. Furthermore, intelligence can provide alternative, secular pathways to meeting the deep psychological needs for control, purpose, and security that religion has traditionally fulfilled, making faith less psychologically necessary for some.

However, this is far from the whole story. The correlation is small, rendering it useless for judging any individual. It is culturally limited, telling us more about belief in the modern West than about faith in general. And most importantly, it is based on a narrow definition of what it means to be "smart."

When we broaden our perspective to include emotional and spiritual intelligence, the picture flips. The very same religious traditions that may be at odds with cold, analytical reasoning can serve as powerful incubators for the "warmer" intelligences of empathy, compassion, emotional regulation, and the search for meaning.

The science, therefore, does not paint a simple caricature of smart atheists versus dumb believers. Instead, it reveals the rich and varied cognitive toolkit that humans deploy to navigate the world. Some individuals may reason their way out of faith, while others feel their way into it. Some find meaning in the elegant logic of a scientific equation, while others find it in the profound compassion of a spiritual teaching. The ultimate question is not about who is smarter, but about the diverse cognitive and emotional pathways that different people, with their different minds, take to find order, community, and meaning in their lives.