Breaking: Intelligence and Religion – Negatively Related

Average intelligence predicts atheism rates across 137 nations

1. Introduction

Dawkins’ (2006) recent book The God Delusion suggests that it is not intelligent to believe in the existence of God. In this paper we examine (1) the evidence for this contention, i.e. for whether there is a negative relationship between intelligence and religious belief; (2) whether the negative relationship between intelligence and religious belief is a difference in Psychometric g; and (3) whether there is negative relationship between intelligence and religious belief between nations.

2. Intelligence and religious belief within nations

We are by no means the first to suggest the existence of a negative relationship between intelligence and religious belief within nations. This phenomenon was observed in the 1920s by Howells (1928) and Sinclair (1928), who both reported studies showing negative correlations between intelligence and religious belief among college students of − .27, and − .29 to − .36 (using different measures of religious belief). In the 1950s Argyle (1958) concluded that “intelligent students are much less likely to accept orthodox beliefs, and rather less likely to have pro-religious attitudes”.

Evidence pointing to a negative relationship between intelligence and religious belief within nations comes from four sources. These are (1) negative correlations between intelligence and religious belief; (2) lower percentages holding religious beliefs among intelligence elites compared with the general population: (3) a decline of religious belief with age among children and adolescents as their cognitive abilities increase; (4) a decline of religious belief during the course of the twentieth century as the intelligence of populations has increased.

2.1. (1) Negative correlations between intelligence and religious belief

A number of studies find negative correlations between intelligence and religious belief. A review of these carried out by Bell (2002) found 43 studies, of which all but four found a negative correlation. To these can be added a study in the Netherlands of a nationally representative sample (total N = 1538) that reported that agnostics scored 4 IQs higher than believers (Verhage, 1964). In a more recent study Kanazawa (in press) has analysed the data of the American National Longitudinal Study of Adolescent Health, a national sample initially tested for intelligence with the PPVT (Peabody Picture Vocabulary Test) as adolescents and interviewed as young adults in 2001–2 (N = 14,277). At this interview they were asked: “To what extent are you a religious person?” The responses were coded “not religious at all”, “slightly religious”, “moderately religious”, and “very religious”. The results showed that the “not religious at all” group had the highest IQ (103.09), followed in descending order by the other three groups (IQs = 99.34, 98.28, 97.14). The relationship between IQ and religious belief is highly significant (F (3, 14273) = 78.0381, p < .00001).

2.2. (2) Lower percentages holding religious beliefs among intelligence elites compared with the general population

In corroboration of these studies finding negative correlations between intelligence and religious belief is evidence comparing the percentages of religious believers among intelligence elites compared with the general population. This was shown as early as 1921 in a survey of the religious beliefs of eminent American scientists and scholars that reported that 39% stated that they believed in God (with a range of 48% among historians to 24% among psychologists) (Leuba, 1921). It was reported by Roe (1965) that among a group of 64 eminent scientists, 61 were “indifferent to religion”, leaving approximately 4.8% as religious believers. These are much lower than the percentage religious believers in the population among whom 95.5% in the United States stated that they believed in God in a 1948 Gallup Poll (Argyle, 1958). In the 1990s a study of members of the American National Academy of Sciences reported that 7% believed in the existence of God, as compared with approximately 90% found in a poll of the general population (Larsen & Witham, 1998). In Britain, it has been reported that 3.3% of Fellows of the Royal Society believed in the existence of God, while 78.8% did not believe (the remainder being undecided) (Dawkins, 2006). At the same time a poll showed that 68.5% of the general population believed in the existence of God.

2.3. (3) Decline of religious belief with age among children and adolescents

Also consistent with the negative correlation between intelligence and religious belief is the decline in religious belief during adolescence and into adulthood as cognitive ability increases. This has been found in the United States for the age range of 12–18 year olds by Kuhlen and Arnold (1944) who reported that among 12 year olds 94% endorsed the statement “I believe there is a God”, while among 18 year olds this had fallen to 78%. Similarly, in England Francis (1989) has found a decline in religious belief over the age range 5–16 years. Religious belief was measured by a scale consisting of questions like “God means a lot to me” and “I think that people who pray are stupid”, etc., and the scores on the scale are shown in abbreviated form in Table 1. The finding that girls score higher than boys has frequently been found (see e.g. Argyle, 1958). In another study, among 12–15 year olds at a Protestant school in Northern Ireland, favourable attitudes to religion fell steadily and significantly (p < .001) with each year of age by approximately 0.75 of a standard deviation over the 4 year period, while the correlations between a favourable attitude to religion and IQ turned increasingly and significantly negative (p < .001) (Turner, 1980). These results are summarized in Table 2. (These trends were less clear for a Roman Catholic school).

Table 1.

Decline in percentage holding religious belief, with age (Francis, 1989)

Age N Boys Girls
5–6 400 87.9 96.0
11–12 400 79.6 84.1
15–16 400 55.7 70.4

Table 2.
Declining belief correlates with age (sd = 15.6)(Turner,1980)

Age N Belief (%) R: non-belief x IQ
12 50 69.54 0.183
13 50 66.10 0.110
14 50 59.86 − 0.113
15 50 57.94 − 0.354low asterisk

low asterisk Significant at p < .01.

2.4. (4) Decline of religious belief during the course of the twentieth century as the intelligence of the population has increased

There is evidence for a decline of religious belief during the course of the last 150 or so years, while at the same time the intelligence of the population has increased. The increase in intelligence is a well-documented phenomenon that has become known as the Flynn effect. The decline of religious belief has been shown by statistics for church attendance and for belief in God recorded in opinion polls. For instance, in England self reported weekly attendance at church services in census returns (these numbers may be exaggerated) declined from 40% of the population in 1850, to 35% in 1900, to 20% in 1950, to 10% in 1990 (Giddens, 1997, p.460); Church of England Easter week communicants declined from 9% of the population in 1900 to 5% in 1970 (Argyle & Beit-Hallahmi, 1975); the attendance of children at Sunday schools declined from 30% of the child population in 1900 to 13% in 1960 (Goldman, 1965). In Gallup Polls 72% of the population stated in 1950 that they believed in God (Argyle, 1958), but by 2004 this had fallen to 58.5% (Zuckerman, 2007).

There has also been some decline of religious belief during the course of the last century in the United States. Hoge (1974) has reviewed several surveys that have found a decline of religious belief in college students. For instance, students at Bryn Mawr were asked whether they believed in a God who answered prayers. Positive responses were given by 42% of students in 1894, 31% in 1933, and 19% in 1968. Students enrolling at the University of Michigan were invited to provide a “religious preference”. In 1896, 86% of students did so; in 1930 this had dropped to 70%, and in 1968 it had dropped to 44%. At Harvard, Radcliffe, Williams and Los Angles City College the percentages of students who believed in God, prayed daily or fairly frequently, and attended church about once a week all declined from 1946 to 1966. Heath (1969) has also reported a decline in belief in God among college students from 79% in 1948 to 58% in 1968. Among the general population, Gallup Polls have found that 95.5% stated that they believed in God in 1948 (Argyle, 1958), but by 2004 this had fallen to 89.5% (Zuckerman, 2007).

3. Religious belief and psychometric g

To determine whether there is negative relation between religious belief and Psychometric g (the general factor in intelligence), the data from the National Longitudinal Study of Youth (NLSY97) have been analysed. The NLSY97 is a national sample selected to represent approximately 15 million American adolescents in the age range of 12–17 years in 1997. The subjects (N = 6825) were asked about current religious preferences in addition and took the Computer Adaptive form of the Armed Services Vocational Aptitude Battery (CAT-ASVAB97). This test consists of twelve scales (10 power and 2 speeded). These were analysed in terms of Raschian probabilistic modelling and the resulting one-dimensional scale correlated .992 (Psychometric R) with general intelligence, g, (Principal Axis Factor Analysis (t(N − 2) = 662.62; p < .000). Atheists scored 6 g-IQ equivalent points higher than the combined group of subjects professing to one or another of a large number of different religions. The difference in general intelligence among atheists and believers was significant even without using weighted data (t(1, 6.893) = 2.87; p = .004).

4. Intelligence and religious belief between nations

To investigate the relationship between intelligence and religious belief between nations we have taken the IQs of nations given in Lynn and Vanhanen’s (2006) IQ and Global Inequality. This source shows that these national IQs have high reliability, as shown by the correlation of .92 between different measures, and high validity, as shown by the correlation of .83 between the IQs and educational attainment. The high reliability and validity of these national IQs have been confirmed by Rindermann (2007). We have taken figures for belief in God from Zuckerman (2007) who gives data for 137 countries representing just over 95% of the world’s population. These data were collected from surveys mostly carried out in 2004, although in a few countries the surveys were a year or two earlier. Zuckerman collated these data from a number of different surveys in order to provide results that were as up-to-date as possible. Where he published more than one survey result for a given country we took the most recent one where this was indicated, but averaged them out where it was not. Zuckermans figures consist of the percentages saying that they disbelieved in God, rather than the more frequent question asking for belief in God. Zuckerman draws attention to four problems associated with this data set. These are possible low response rates, weaknesses in random sample selection, regime or peer pressure influencing responses and problems of terminological variation between cultures over words such as ‘religious’ or ‘secular’. Despite these possible sources of error however Zuckerman urges acceptance of the data by quoting Robert Putnam to the effect that “we must make do with the imperfect evidence that we can find, not merely lament its deficiencies.”

The data for the national IQs and percentages asserting disbelief in God for the 137 countries are given in the Appendix A. It will be seen that in only 17% of the countries (23 out of 137) does the proportion of the population who disbelieve in God rise above 20%. These are virtually all the higher IQ countries.

The correlations between the national IQs and religious disbelief are given in Table 3. Row 1 gives the correlation of 0.60 for the total sample and is highly statistically significant (p < .001). To examine whether this relationship holds across the whole range of national IQs we have divided the nations into two groups of those with IQs between 64–86 and those with IQs between 87–108. Row 2 gives the data for the 69 countries with IQs between 64–86. In this group only 1.95% of the population are non-believers. There is a range between < 1% and 40%, and the correlation between the two variables is only 0.16. Row 3 gives the data for the 68 countries with IQs between 87–108. In this group 19.99% of the population disbelieve in God. There is a range between < 1% and 81%, and the correlation between the two variables is only 0.54 (p < .001). Thus, most of the variation in religious disbelief is among the higher IQ nations.

Table 3.
Correlations between the national IQs and religious disbelief

Iqs N countries Non-believers Range non-believers R: non-belief x IQ
64–108 137 10.69% < 1% to 81% + 0.60
64–86 69 1.95% < 1% to 40% + 0.16
87–108 68 16.99% < 1% to 81% + 0.54

5. Discussion

The results raise four points of interest. First, the hypothesis with which we began this study was that there is a negative correlation between IQ and religious belief. We have reviewed considerable evidence for this negative relationship among individuals in the United States and Europe and have added a new data set confirming this. Second, we have shown that the negative relationship between intelligence and religious belief is a difference in Psychometric g. Third, we have extended this hypothesis to an examination of whether a negative correlation between IQ and religious belief is present between countries. Using data from 137 countries we found a correlation of 0.60 between national IQs and disbelief in God. Although the measure used for the analysis across nations was for disbelief in God rather than for belief in God, we believe it can be reasonably assumed that disbelief in God is highly (negatively) correlated with belief in God. Hence, we conclude that the negative correlation between IQ and religious belief that has been found in numerous studies within nations is also present between nations.

Second, this conclusion raises the question of why should there be this negative correlation between IQ and belief in God. Many rationalists no doubt accept the argument advanced by Frazer (1922, p.712) in The Golden Bough that as civilisations developed “the keener minds came to reject the religious theory of nature as inadequate … religion, regarded as an explanation of nature, is replaced by science” (by “keener minds” Frazer presumably meant the more intelligent). Others have assumed implicitly or explicitly that more intelligent people are more prone to question irrational or unprovable religious dogmas. For instance, some 60 years ago Kuhlen and Arnold (1944) proposed that “greater intellectual maturity might be expected to increase scepticism in matters of religion”. Inglehart and Welzel (2005, p.27) suggest that in the pre-industrial world, humans have little control over nature, so “they seek to compensate their lack of physical control by appealing to the metaphysical powers that seem to control the world: worship is seen as a way to influence one’s fate, and it is easier to accept one’s helplessness if one knows the outcome is in the hands of an omnipotent being whose benevolence can be won by following rigid and predictable rules of contact…one reason for the decline in traditional religious beliefs in industrial societies is that an increasing sense of technological control over nature diminishes the need for reliance on supernatural powers”.

Third, there are a few exceptions to the generally linear relationship between IQ and disbelief in God across nations. Two of the most anomalous are Cuba and Vietnam, which have higher percentages disbelieving in God (40% and 81%, respectively) than would be expected from their IQs of 85 and 94 (respectively). This is likely attributable to these being former or current communist countries in which there has been strong atheistic propaganda against religious belief. In addition, it has sometimes been suggested that communism is itself a form of religion in which Das Capital is the sacred text, Lenin was the Messiah who came to bring heaven on earth, while Stalin, Mao, Castro and others have been his disciples who have came to spread the message in various countries. On these grounds, it may be argued that many of the peoples of Cuba and Vietnam hold a variant of more conventional religious belief in God.

Fourth, the United States is anomalous in having an unusually low percentage of its population disbelieving in God (10.5%) for a high IQ country. The percentage disbelieving in God in the United States is much lower than in north west and central Europe (e.g. Belgium, 43%; Netherlands, 42%; Denmark, 48%; France, 44%; UK, 41.5%). One factor that could provide a possible explanation for this is that many Americans are Catholics, and the percentage of believers in Catholic countries in Europe is generally much higher than in Protestant countries (e.g. Italy, 6%; Ireland, 5%; Poland, 3%; Portugal, 4%; Spain, 15%). Another possible contribution to this has been continued high immigration of those holding religious beliefs. A further possible factor might be that a number of emigrants from Europe went to the United States because of their strong religious beliefs, so it may be that these beliefs have been transmitted as a cultural and even genetic legacy to subsequent generations. Parent–child correlations for religious belief are quite high at 0.64 (fathers–sons) and 0.69 (mothers–daughters) (Newcomb & Svehla, 1937). It has been found that religious belief has a significant heritability of around 0.40–0.50 (Koenig, McGrue, Krueger & Bouchard, 2005), so it could be that a number of religious emigrants from Europe had the genetic disposition for religious belief and this has been transmitted to much of the present population.


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Appendix A

Country IQ % not believing in God
Afghanistan 84 0.5
Albania 90 8
Algeria 83 0.5
Angola 68 1.5
Argentina 93 4
Armenia 94 14
Australia 98 25
Austria 100 18
Azerbaijan 87 0.5
Bangladesh 82 0.5
Belarus 97 17
Belgium 99 43
Benin 70 0.5
Bolivia 87 1
Botswana 70 0.5
Brazil 87 1
Brunei 91 0.5
Bulgaria 93 34
Burkina Faso 68 0.5
Burundi 69 0.5
Cambodia 91 7
Cameroon 64 0.5
Canada 99 22
Central African Rep. 64 1.5
Chad 68 0.5
Chile 90 2
China 105 12
Colombia 84 1
Congo: Rep of (Brazz) 64 2.7
Costa Rica 89 1
Cote d’Ivoire 69 0.5
Croatia 90 7
Cuba 85 40
Czech Republic 98 61
Denmark 98 48
Dominican Republic 82 7
Ecuador 88 1
Egypt 81 0.5
El Salvador 80 1
Estonia 99 49
Ethiopia 64 0.5
Finland 99 28
France 98 44
Gambia 66 0.5
Georgia 94 4
Germany 99 42
Ghana 71 0.5
Greece 92 16
Guatemala 79 1
Guinea 67 0.5
Haiti 67 0.5
Honduras 81 1
Hungary 98 32
Iceland 101 16
India 82 3
Indonesia 87 1.5
Iran 84 4.5
Iraq 87 0.5
Ireland 92 5
Israel 95 15
Italy 102 6
Jamaica 71 3
Japan 105 65
Jordan 84 0.5
Kazakhstan 94 12
Kenya 72 0.5
Kuwait 86 0.5
Kyrgyzstan 90 7
Laos 89 5
Latvia 98 20
Lebanon 82 3
Liberia 67 0.5
Libya 83 0.5
Lithuania 91 13
Madagascar 82 0.5
Malawi 69 0.5
Malaysia 92 0.5
Mali 69 0.5
Mauritania 76 0.5
Mexico 88 4.5
Moldova 96 6
Mongolia 101 20
Morocco 84 0.5
Mozambique 64 5
Namibia 70 4
Nepal 78 0.5
Netherlands 100 42
New Zealand 99 22
Nicaragua 81 1
Niger 69 0.5
Nigeria 69 0.5
Norway 100 31
Oman 83 0.5
Pakistan 84 0.5
Panama 84 1
Paraguay 84 1
Peru 85 1
Philippines 86 0.5
Poland 99 3
Portugal 95 4
Romania 94 4
Russia 97 27
Rwanda 70 0.5
Saudi Arabia 84 0.5
Senegal 66 0.5
Sierra Leone 64 0.5
Singapore 108 13
Slovakia 96 17
Slovenia 96 35
Somalia 68 0.5
South Africa 72 1
South Korea 106 30
Spain 98 15
Sri Lanka 79 0.5
Sweden 99 64
Switzerland 101 17
Syria 83 0.5
Taiwan 105 24
Tajikistan 87 2
Tanzania 72 0.5
Thailand 91 0.5
Togo 70 0.5
Trinidad and Tobago 85 9
Tunisia 83 0.5
Turkmenistan 87 2
Uganda 73 0.5
Ukraine 97 20
United Arab Emirates 84 0.5
United Kingdom 100 41.5
United States 98 10.5
Uruguay 96 12
Uzbekistan 87 4
Venezuela 84 1
Vietnam 94 81
Yemen 85 0.5
Zambia 71 0.5
Zimbabwe 66 4