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At one point in the prehistory of our species, no one
believed in a god. Today, an estimated 80% of humans
are theists (P. Zuckerman, 2007). Why did the belief in
gods become so broadly and powerfully held? Religion
has fascinated psychologists since James (1902), but a
recent body of research has sharply focused on the
reasons people believe in gods—defined here as
“supernatural beings believed to have created or [to]
govern all reality, intervene in human affairs, and
enforce or support human morality” (Botero etal., 2014,
p. 16784). Here, we separate these reasons along Mayr’s
(1961) ultimate versus proximate categorization of
causal explanations. Ultimate explanations focus on
why a behavior evolved—its functional origins as an
adaptation or evolutionary by-product. Proximate expla-
nations focus on the immediate factors influencing how
and when a behavior is performed. For example, the
proximate explanation for a bird undertaking its yearly
migration is the experience of changing daily hours of
sunlight, but the ultimate explanation is that because
of the scarce winter food supply, better survival and
reproductive opportunities were afforded to those who
migrated to warmer climates.
Ultimate and proximate causes thus provide comple-
mentary—rather than competing—explanations for a
behavior. Although not without critics (see Vromen, 2017,
for a discussion), the ultimate-proximate distinction has
proved useful for preventing confusion about different
types of causation (Scott-Phillips, Dickins, & West, 2011).
For example, a question posed at one level of explanation
cannot be answered at another level of explanation. An
ultimate question about why cooperation exists requires
an explanation for the evolution of cooperation, such as
that it provides a selective advantage by increasing the
fitness of one’s kin. It cannot be answered with a proxi-
mate explanation for cooperation, such as concerns for
praise and blame (Scott-Phillips etal., 2011). This ultimate-
proximate distinction thus provides a useful organizing
framework for recent research on the belief in God.
Ultimate Reasons for the Cognitive
Features Making Belief in God Intuitive
Features of the human mind have arisen as evolved
adaptations to environmental challenges throughout our
prehistory. However, many authors have argued that
these cognitive adaptations have, as a by-product, made
humans prone to the conception of supernatural agents
(Norenzayan etal., 2016). An early, oft-cited example
of such a cognitive adaptation is our hypersensitivity to
754491CDPXXX10.1177/0963721418754491Mercier et al.Belief in God
Azim F. Shariff, University of California, Irvine, Department of
Psychology and Social Behavior, 4558 Social and Behavioral Sciences
Gateway, Irvine, CA 92697
Belief in God: Why People Believe,
and Why They Don’t
Brett Mercier1, Stephanie R. Kramer2, and Azim F. Shariff1
1Department of Psychology and Social Behavior, University of California, Irvine, and 2Department of Psychology,
University of Oregon
Belief in a god or gods is a central feature in the lives of billions of people and a topic of perennial interest within
psychology. However, research over the past half decade has achieved a new level of understanding regarding both
the ultimate and proximate causes of belief in God. Ultimate causes—the evolutionary influences on a trait—shed light
on the adaptive value of belief in God and the reasons why a tendency toward this belief exists in humans. Proximate
causes—the immediate influences on the expression of a trait—explain variation and changes in belief. We review this
research and discuss remaining barriers to a fuller understanding of belief in God.
belief, God, evolution, religion
2 Mercier et al.
cues of humanlike agency (Guthrie, 1993). Because failing
to notice potentially dangerous agents in our ancestral envi-
ronment was costlier than making false alarms, our agency-
detection system evolved to be tilted toward overperception.
But the by-product of being adaptively tuned to overper-
ceive agency is that humans are biased toward perceiving
agents—such as gods—behind natural phenomena.
Alongside this hypersensitive agency-detection
device, theorists have described biases for overperceiv-
ing human-relevant purposes behind events and
objects—adaptive because of the necessity of decipher-
ing intentionality and the usefulness of understanding
tools but leading in turn to a tendency to make attribu-
tions of divine purpose (Kelemen, 2004). In addition,
because of the importance of understanding mental
states, humans evolved separate systems for thinking
about social stimuli and physical, nonsocial objects
(Bloom, 2007). Although this was adaptive for our
social cognition, a by-product was that it made it easy
for humans to imagine the existence of disembodied
supernatural agents that nonetheless had an active
mental existence (Forstmann & Burgmer, 2015).
These by-products of innately occurring cognitive
features provided the psychological raw materials from
which supernatural beliefs were culturally shaped into
shared God beliefs (Gervais, Willard, Norenzayan, &
Henrich, 2011). Unlike the gods of most modern reli-
gions, the supernatural agents that early societies
believed in tended to be nonmoralistic, with limited
powers and knowledge (Roes & Raymond, 2003). To
explain the transition, cultural evolutionary theorists
have argued that, in a process roughly analogous to
genetic evolution, selective pressures made certain cul-
tural beliefs more likely to survive and spread than
others. As human group sizes increased, it became dif-
ficult to track which members were cooperative con-
tributors and which were defecting free riders, straining
the mechanisms maintaining group cohesion. Beliefs
in omniscient supernatural watchers capable of doling
out punishments and rewards helped solve this problem
by deterring free riding, giving groups adopting these
beliefs an advantage over other groups (Norenzayan
etal., 2016; though see the commentaries to that article
for criticisms and alternative perspectives). In a recent
cross-cultural study demonstrating this religiously
inspired prosociality, researchers found that the more
individuals believed their gods were punitive and
knowledgeable about humans, the more money these
individuals shared with anonymous coreligionists in an
economic game (Purzycki etal., 2016). In another study,
subtle reminders of God made people more charitable,
but only when these reminders were of God’s punitive
aspects (Yilmaz & Bahçekapili, 2016).
Thus, increased cooperation made groups who
believed in watchful, moralizing gods more likely to
survive and spread their beliefs, making these beliefs
more common. Analysis of historical societies has found
that these beliefs were especially likely to spread where
the need for cooperation was high, such as in societies
with rights to movable property, high political complex-
ity, or resource scarcity (Botero etal., 2014).
Proximate Reasons for Who Believes
While ultimate explanations tell us why specific cogni-
tive biases evolved, proximate explanations show how
and when these biases contribute to belief in God.
Understanding these cognitive, motivational, and
social factors that influence belief helps explain the
great variation in religiosity among our species—not
just across countries (84% of people in the Philippines
report being certain about God’s existence, compared
with 4% in Japan; Smith, 2012) but across time—which
can in turn inform long-standing debates about
One method of examining the proximate cognitive fac-
tors influencing belief in God is to compare individuals
who differ on cognitive factors, such as the tendency
to rely on evolved cognitive intuitions. People with an
analytical thinking style—that is, people more likely to
override their intuitions in decision making—are less
likely to be believers (Pennycook, Ross, Koehler, &
Fugelsang, 2016). In addition to overriding intuitions,
the extent to which people experience these intu-
itions in the first place also plays a role. Because
attributing mental states to unseen agents facilitates
belief in God, people who less easily perceive and
understand the mental states of others (such as indi-
viduals on the autism spectrum and men relative to
women) show lower levels of belief (Norenzayan,
Gervais, & Trzesniewski, 2012).
Though still controversial, convergent research sug-
gests that more intelligent individuals are less likely to
believe in God (Kanazawa, 2010; Lynn, Harvey, & Nyborg,
2009). Although partially explained by its overlap with
analytic thinking, the relationship between belief in God
and intelligence also has compelling motivation-based
explanations. For example, M. Zuckerman, Silberman,
and Hall (2013) argue that more intelligent individuals
may have less need for the psychological benefits that
religion provides (such as a sense that the world is
controllable; see below) because they can more ably
generate these benefits themselves. Intelligent people
are also more likely to be nonconformists and thus feel
more comfortable deviating from the (typically) reli-
Belief in God 3
In addition to studying the factors that make people
more or less cognitively receptive to belief in God,
research has also examined the factors that motivate
(or demotivate) people to believe. For instance,
Sedikides and Gebauer (2010) present a meta-analysis
showing that high self-enhancers—people with a strong
desire to see themselves positively—have higher levels
of intrinsic religiosity, especially in societies that place
greater value on religion. They argue that elements of
religion—such as a believed association with God—
create feelings of positive self-regard, motivating high
self-enhancers to adopt stronger religious beliefs. How-
ever, more research is needed to confirm this causal
Other research has used experiments to provide a
causal test of motivational factors influencing belief.
Epley and colleagues show not only that chronically
lonely people are less likely to believe in God but also
that randomly assigning people to situations that
increase loneliness (such as informing people that they
will probably be alone later in life) increases reports
of belief (Epley, Akalis, Waytz, & Cacioppo, 2008).
Compensatory-control theory posits that people
strive to believe their world is predictable and control-
lable (Kay, Gaucher, Napier, Callan, & Laurin, 2008).
On the basis of this theory, Kay and colleagues (2008)
argue that belief in God is motivated by a need for
perceived control, which they demonstrated by showing
that experimentally threatening people’s sense of con-
trol can increase belief in God. Experimentally increas-
ing mortality salience has also been shown to increase
belief (Vail, Arndt, & Abdollahi, 2012), which may
explain why religiosity tends to increase when people
get older, become terminally ill, or experience a natural
disaster (Bentzen, 2013; Jong, 2013). The ability of the
belief in God—and religion more generally—to palliate
the effect of negative life events has been offered as
one explanation for religiosity’s association with greater
well-being (Whitehead & Bergeman, 2011).
Together, these cognitive and motivational factors
help explain where and when belief in God has
declined around the world. For example, some research-
ers have argued that the declines in belief over the 20th
century can be explained by the corresponding
increases in IQ over this same period (Lynn etal.,
2009). Likewise, religiosity has tended to decline when
strong and predictable political systems dampen the
uncertainty and adversity in a society. The religiosity
of the United States, which is aberrantly high among
rich countries, has been attributed to the sense of eco-
nomic insecurity caused by its (relatively) laissez faire
economic policies (Norris & Inglehart, 2004).
Finally—but critically—declines in belief are acceler-
ated by feedback loops with changing cultural norms.
In religious societies, people are socialized to believe
in God through communities that value and encourage
belief (Sherkat, 2003). This socialization, particularly
the religious behaviors of one’s community, appears to
be one of the strongest determinants of belief. Accord-
ing to Henrich (2009), humans evolved to be acutely
sensitive to credibility-enhancing displays in their ten-
dency to adopt beliefs. For example, claims that blue
mushrooms are not poisonous are more credible when
the claimant eats the mushrooms (Henrich, 2009). Con-
sistent with this theory, research has shown that the
more frequently children observe others not just pro-
fessing belief in God but engaging in religious credibility-
enhancing displays (such as volunteering for religious
organizations), the more likely these children are to
believe in God as adults (Lanman & Buhrmester, 2017).
Thus, once triggered, generational declines in belief in
God might gain momentum through a positive feedback
effect. Children of each generation are raised witness-
ing fewer displays of religious commitment than the
last, making them less likely to believe in God and less
likely to expose their own children to displays of com-
mitment (Willard & Cingl, 2017; see Fig. 1).
Limitations With the Literature
Though the past 5 years have seen remarkable progress
in the psychology underlying belief in God, a more
complete understanding of the phenomenon has been
hampered by significant limitations in interpreting what
is by far the primary source of data about beliefs in
The first issue derives from a Western and Abrahamic
bias in the psychology of religion. Efforts to conduct
research outside the monotheistic, Judeo-Christian reli-
gious traditions in North America and Europe are limited
not just by inconvenience and political restrictions (e.g.,
in China and several Muslim-majority countries) but also
by conceptual differences in the meaning of belief. That
is, methods of measuring belief in God that assume a
traditional Western conception of God may not be
appropriate for understanding the beliefs of people with
different conceptions of God (Höllinger & Eder, 2016).
These cultural variations in the meaning of belief are
rarely assessed (for a notable exception, see Bluemke,
Jong, Grevenstein, Mikloušic´, & Halberstadt, 2016). How
similar is an American Christian’s belief in a personal
God to the Vedic theistic beliefs in India or to ancestor
worship in China? Although someone from each country
may answer affirmatively to straightforward questions
Evolved Cognitive Biases
Hypersensitive agency detection: Over-
perception of agency leads to the perception
that God is causing natural events.
Promiscuous teleology: Overperception of
purpose leads to attributions of divine purpose
in the world.
Mind–body dualism: Perceiving minds as
separate from bodies makes it easy to
conceive of disembodied supernatural
Belief in punitive, monitoring gods provided
a survival advantage by increasing in-group
cooperation, making these beliefs more
These beliefs were most likely to spread
when cooperation was important, such as in
societies with few resources, rights to
movable property, and high political
Socialization (+): People are more likely to believe in
God when this belief is valued and encouraged by their
Credibility-enhancing displays (+): Witnessing credible
displays of religious commitment increases the likelihood
of believing in God.
Loneliness (+): When lonely, people are more likely to
perceive agents, including God.
Mortality salience (+): Belief increases when death is salient.
Self-enhancement (+): In places where religion is
valued, a desire to see oneself positively motivates belief
Control (–): Belief in a controlling God increases in
uncontrollable situations, allowing people to regain a
sense of control.
Analytical thinking style (–): Analytical thinkers are less
likely to be inﬂuenced by the cognitive intuitions
contributing to belief in God.
Mentalizing (+): People more capable of mind reading
are more likely to perceive the existence of God.
Intelligence (–): People with higher intelligence are
less likely to believe in God.
Fig. 1. An overview of ultimate and proximate factors contributing to belief in God. On the right-hand side of the figure, a plus sign denotes that the factor increases the likeli-
hood of belief, whereas a minus sign denotes that the factor decreases the likelihood of belief.
Belief in God 5
about belief in “God” (if only to conform to Western
surveyors’ expectations), it remains unclear whether
these homogenous responses disguise psychologically
Even in Western contexts, the continued evolution
of religion has led to widening conceptions of God,
which may not cleanly correspond to traditional beliefs.
For example, 30% of Europeans, including many self-
described “atheists,” report believing in a “spirit God or
vital life force” (Bréchon, 2007, p. 469). Should this
quasideism be defined as belief in God? Clearly, tradi-
tional methods are not fully capturing the scope and
meaning of belief in these contexts.
The other major challenge to the integrity of self-
report-based research on belief in God is that reports
may reflect self-presentation concerns as much as genu-
ine belief. Around the world, people show considerable
prejudice against nonbelievers (Gervais etal., 2017),
and majorities consider belief necessary for morality
(Pew Research Center, 2014). Thus, people may be
inclined to present themselves as more religious than
they truly are. Evidence of exaggeration in church
attendance supports this concern—as evidenced by
discrepancies between direct self-reports and head
counts (Hadaway, Marler, & Chaves, 1993) or time-use
diaries (Brenner, 2011). And though it is harder to con-
firm the veracity of people’s internal beliefs than their
behavior, research supports the idea that people are
indeed overreporting their belief in God. Survey tech-
niques that decrease socially desirable responding, such
as responding anonymously online rather than directly
to a live surveyor (Cox, Jones, & Navarro-Rivera, 2014)
or using the unmatched-count technique (Gervais &
Najle, 2018), suggest that rates of belief may be sub-
stantially lower than traditional methods have assumed.
The potential invalidity of self-reported belief calls
into question the interpretation of many findings within
the social scientific literature on religion. Consider
research that finds relationships between God beliefs
and any construct that might be misreported because
of social pressure (e.g., happiness, health, prosociality).
Any correlation between belief in God and (for exam-
ple) happiness may be the result not of a genuine
relationship between the two but of a third variable:
individual differences in people’s tendency to overre-
port levels of both. Furthermore, experimental studies—
including those discussed above—that show changes
in self-reported belief in God could very well be reveal-
ing changes in people’s willingness to admit their belief
rather than changes in belief itself.
These methodological questions should weigh heav-
ily on the field. The past 5 years have seen an expanding
body of research on belief in God; researchers should
devote some of the next 5 to tackling these critical chal-
lenges. Until we do, we will not fully understand the
extent, nature, or future of how belief in God factors
into our psychology and society.
Norenzayan, A., Shariff, A. F., Gervais, W. M., Willard, A. K.,
McNamara, R. A., Slingerland, E., & Henrich, J. (2016).
(See References). An in-depth review of the cultural evo-
lution of religion plus an assortment of commentaries that
discuss additional and alternative perspectives.
Norris, P., & Inglehart, R. (2004). (See References). A review
of the causes and consequences of secularization around
Sedikides, C. (2010). Why does religiosity persist? Personality
and Social Psychology Review, 14, 3–6. The introduction
to the 2010 Personality and Social Psychology Review spe-
cial issue on religion, which provides a summary and
overview of the approaches contained within the issue.
Zuckerman, M., Silberman, J., & Hall, J. A. (2013). (See
References). A meta-analysis, comprehensive review,
and theoretical discussion of the research examining the
relationship between intelligence and religiosity.
Randall W. Engle served as action editor for this article.
Declaration of Conflicting Interests
The author(s) declared that there were no conflicts of interest
with respect to the authorship or the publication of this
Bentzen, J. S. (2013). Origins of religiousness: The role of natu-
ral disasters (Discussion Paper No. 13-02). Copenhagen,
Denmark: Department of Economics, University of
Bloom, P. (2007). Religion is natural. Developmental Science,
Bluemke, M., Jong, J., Grevenstein, D., Mikloušic´, I., &
Halberstadt, J. (2016). Measuring cross-cultural supernatu-
ral beliefs with self- and peer-reports. PLOS ONE, 11(10),
Article e0164291. doi:10.1371/journal.pone.0164291
Botero, C. A., Gardner, B., Kirby, K. R., Bulbulia, J., Gavin,
M. C., & Gray, R. D. (2014). The ecology of religious
beliefs. Proceedings of the National Academy of Sciences,
USA, 111, 16784–16789.
Bréchon, P. (2007). Cross-national comparisons of individual
religiosity. In J. A. Beckford & N. J. Demerath, III (Eds.),
The SAGE handbook of the sociology of religion (pp. 463–
489). London, England: SAGE.
Brenner, P. S. (2011). Identity importance and the overreport-
ing of religious service attendance: Multiple imputation of
religious attendance using the American Time Use Study
and the General Social Survey. Journal for the Scientific
Study of Religion, 50, 103–115.
Cox, D., Jones, R. P., & Navarro-Rivera, J. (2014). I know what
you did last Sunday: Measuring social desirability bias
in self-reported religious behavior, belief, and identity.
Public Religion Research Institute, 2, 57–58.
6 Mercier et al.
Epley, N., Akalis, S., Waytz, A., & Cacioppo, J. T. (2008). Creating
social connection through inferential reproduction:
Loneliness and perceived agency in gadgets, gods, and
greyhounds. Psychological Science, 19, 114–120.
Forstmann, M., & Burgmer, P. (2015). Adults are intuitive
mind-body dualists. Journal of Experimental Psychology:
General, 144, 222–235.
Gervais, W. M., & Najle, M. B. (2018). How many atheists are
there? Social Psychological and Personality Science, 9, 3–10.
Gervais, W. M., Willard, A., Norenzayan, A., & Henrich, J.
(2011). The cultural transmission of faith: Why innate
intuitions are necessary, but insufficient, to explain reli-
gious belief. Religion, 41, 389–410.
Gervais, W. M., Xygalatas, D., McKay, R. T., van Elk, M.,
Buchtel, E. E., Aveyard, M., . . . Bulbulia, J. (2017).
Global evidence of extreme intuitive moral prejudice
against atheists. Nature Human Behavior, 1, Article 0151.
Guthrie, S. E. (1993). Faces in the clouds: A new theory of
religion. New York, NY: Oxford University Press.
Hadaway, C. K., Marler, P. L., & Chaves, M. (1993). What the
polls don’t show: A closer look at U.S. church attendance.
American Sociological Review, 58, 741–752.
Henrich, J. (2009). The evolution of costly displays, coopera-
tion and religion: Credibility enhancing displays and their
implications for cultural evolution. Evolution & Human
Behavior, 30, 244–260.
Höllinger, F., & Eder, A. (2016). Functional equivalence
and validity of religiousness indicators in cross-cultural
comparative surveys. Methodological Innovations, 9.
James, W. (1902). The varieties of religious experience: A study
in human nature. New York, NY: Penguin.
Jong, J. (2013). On faith and the fear of fatality: A review
of recent research on deities and death. Journal for the
Cognitive Science of Religion, 1, 193–214.
Kanazawa, S. (2010). Why liberals and atheists are more intel-
ligent. Social Psychology Quarterly, 73, 33–57.
Kay, A. C., Gaucher, D., Napier, J. L., Callan, M. J., & Laurin, K.
(2008). God and the government: Testing a compensatory
control mechanism for the support of external systems.
Journal of Personality and Social Psychology, 95, 18–35.
Kelemen, D. (2004). Are children “intuitive theists”? Reasoning
about purpose and design in nature. Psychological
Science, 15, 295–301.
Lanman, J. A., & Buhrmester, M. D. (2017). Religious actions
speak louder than words: Exposure to credibility-enhanc-
ing displays predicts theism. Religion, Brain & Behavior,
Lynn, R., Harvey, J., & Nyborg, H. (2009). Average intelligence
predicts atheism rates across 137 nations. Intelligence,
Mayr, E. (1961). Cause and effect in biology. Science, 134,
Norenzayan, A., Gervais, W. M., & Trzesniewski, K. H. (2012).
Mentalizing deficits constrain belief in a personal God.
PLOS ONE, 7(5), Article e36880. doi:10.1371/journal.pone
Norenzayan, A., Shariff, A. F., Gervais, W. M., Willard, A. K.,
McNamara, R. A., Slingerland, E., & Henrich, J. (2016).
The cultural evolution of prosocial religions [Target article
and commentaries]. Behavioral and Brain Sciences, 39,
Article e1. doi:10.1017/S0140525X14001356
Norris, P., & Inglehart, R. (2004). Sacred and secular: Religion
and politics worldwide. Cambridge, England: Cambridge
Pennycook, G., Ross, R. M., Koehler, D. J., & Fugelsang, J. A.
(2016). Atheists and agnostics are more reflective than
religious believers: Four empirical studies and a meta-
analysis. PLOS ONE, 11(4), Article e0153039. doi:10.1371/
Pew Research Center. (2014, March 13). Worldwide, many
see belief in God as essential to morality. Retrieved from
Purzycki, B. G., Apicella, C., Atkinson, Q. D., Cohen, E.,
McNamara, R. A., Willard, A. K., . . . Henrich, J. (2016).
Moralistic gods, supernatural punishment and the expan-
sion of human sociality. Nature, 530, 327–330.
Roes, F. L., & Raymond, M. (2003). Belief in moralizing gods.
Evolution & Human Behavior, 24, 126–135.
Scott-Phillips, T. C., Dickins, T. E., & West, S. A. (2011).
Evolutionary theory and the ultimate–proximate distinc-
tion in the human behavioral sciences. Perspectives on
Psychological Science, 6, 38–47.
Sedikides, C., & Gebauer, J. E. (2010). Religiosity as self-
enhancement: A meta-analysis of the relation between
socially desirable responding and religiosity. Personality
and Social Psychology Review, 14, 17–36.
Sherkat, D. E. (2003). Religious socialization: Sources of
influence and influences of agency. In M. Dillion (Ed.),
Handbook of the sociology of religion (pp. 151–163). New
York, NY: Cambridge University Press.
Smith, T. W. (2012). Beliefs about God across time and coun-
tries. NORC at the University of Chicago. Retrieved from
Vail, K. E., III, Arndt, J., & Abdollahi, A. (2012). Exploring
the existential function of religion and supernatural agent
beliefs among Christians, Muslims, atheists, and agnostics.
Personality and Social Psychology Bulletin, 38, 1288–1300.
Vromen, J. (2017). Ultimate and proximate explanations
of strong reciprocity. History and Philosophy of the Life
Sciences, 39(3), Article 25. doi:10.1007/s40656-017-0151-4
Whitehead, B. R., & Bergeman, C. S. (2011). Coping with daily
stress: Differential role of spiritual experience on daily
positive and negative affect. Journals of Gerontology, Series
B: Psychological Sciences & Social Sciences, 67, 456–459.
Willard, A. K., & Cingl, L. (2017). Testing theories of secu-
larization and religious belief in the Czech Republic and
Slovakia. Evolution & Human Behavior 38, 604–615.
Yilmaz, O., & Bahçekapili, H. G. (2016). Supernatural and
secular monitors promote human cooperation only if they
remind of punishment. Evolution & Human Behavior, 37,
Zuckerman, M., Silberman, J., & Hall, J. A. (2013). The rela-
tion between intelligence and religiosity: A meta-analysis
and some proposed explanations. Personality and Social
Psychology Review, 17, 325–354.
Zuckerman, P. (2007). Atheism: Contemporary numbers and pat-
terns. In M. Martin (Ed.), The Cambridge companion to athe-
ism (pp. 47–65). New York, NY: Cambridge University Press.