Religiosity, in its broadest sense, is a comprehensive sociological term used to refer to the numerous aspects of religious activity, dedication, and belief (religious doctrine). Another term that would work equally well, though less often used, is religiousness.
In its narrowest sense, religiosity deals more with how religious a person is, and less with how a person is religious (in practicing certain rituals, retelling certain stories, revering certain symbols, or accepting certain doctrines about deities and afterlife).
Numerous studies have explored the different components of human religiosity (Brink, 1993; Hill & Hood 1999). What most have found is that there are multiple dimensions (they often employ factor analysis). For instance, Cornwall, Albrecht, Cunningham and Pitcher (1986) identify six dimensions of religiosity based on the understanding that there are at least three components to religious behavior: knowing (cognition in the mind), feeling (affect to the spirit), and doing (behavior of the body). For each of these components of religiosity there were two cross classifications resulting in the six dimensions:
- traditional orthodoxy
- particularistic orthodoxy
- religious behavior
- religious participation
Other researchers have found different dimensions, ranging generally from four to twelve components. What most measures of religiosity find is that there is at least some distinction between religious doctrine, religious practice, and spirituality.
For example[original research?], one can accept the truthfulness of the Bible (belief dimension), but never attend a church or even belong to an organized religion (practice dimension). Another example is an individual who does not hold orthodox Christian doctrines (belief dimension), but does attend a charismatic worship service (practice dimension) in order to develop his/her sense of oneness with the divine (spirituality dimension).
An individual could disavow all doctrines associated with organized religions (belief dimension), not affiliate with an organized religion or attend religious services (practice dimension), and at the same time be strongly committed to a higher power and feel that the connection with that higher power is ultimately relevant (spirituality dimension). These are explanatory examples of the broadest dimensions of religiosity and that they may not be reflected in specific religiosity measures.
Most dimensions of religiosity are correlated, meaning people who often attend church services (practice dimension) are also likely to score highly on the belief and spirituality dimensions. But individuals do not have to score high on all dimensions or low on all dimensions; their scores can vary by dimension.
Sociologists have differed over the exact number of components of religiosity. Charles Glock's five-dimensional approach (Glock, 1972: 39) was among the first of its kind in the field of sociology of religion. Other sociologists adapted Glock's list to include additional components (see for example, a six component measure by Mervin F. Verbit).
Genes and environment
The contributions of genes and environment to religiosity have been quantified in studies of twins (Bouchard et al., 1999; Kirk et al., 1999) and sociological studies of welfare, availability, and legal regulations  (state religions, etc.).
Koenig et al. (2005) report that the contribution of genes to variation in religiosity (called heritability) increases from 12% to 44% and the contribution of shared (family) effects decreases from 56% to 18% between adolescence and adulthood.
A market-based theory of religious choice and governmental regulation of religion have been the dominant theories used to explain variations of religiosity between societies. However, Gill and Lundsgaarde (2004)  documented a much stronger correlation between welfare state spending and religiosity. See "Welfare spending vs Church attendance" diagram on the right.
Many academic studies have found a negative relationship between religiosity (measured as religious practices, spiritual beliefs, etc.) and intelligence (measured as IQ or EI) – that is, religious believers are generally less intelligent than irreligious people are. A 2013 meta-analysis of scientific studies about IQ and religiosity found a reliable negative relation between intelligence and religiosity in 53 out of 63 studies.
- Importance of religion by country
- Religiosity and intelligence
- Religion and happiness
- Religiosity and education
- The Religiosity Index is a measure of the importance of religion for respondents and their self-reported attendance of religious services. For religions in which attendance at services is limited, care must be used in interpreting the data. (Gallup WorldView), (Religiosity Highest in World's Poorest Nations, Gallup Global Reports, August 31, 2010, retrieved 2014-01-23)
- In 2006, 2007, and 2008, Gallup asked representative samples in 143 countries and territories whether religion was an important part of their daily lives. This map is based on the results, and shows religiosity by country, ranging from the least religious to the most religious on a relative basis. Data from 2009 Gallup poll.
- Pew Research Center Report, 2002
- Cornwall; Albrecht, Cunningham, Pitcher (1986). "The Dimensions of Religiosity: A Conceptual Model with an Empirical Test". Review of Religious Research 27 (3): 226–244. doi:10.2307/3511418.
- Glock, C. Y. (1972) ‘On the Study of Religious Commitment’ in J. E. Faulkner (ed.) Religion’s Influence in Contemporary Society, Readings in the Sociology of Religion, Ohio: Charles E. Merril: 38-56.
- Verbit, M. F. (1970). The components and dimensions of religious behavior: Toward a reconceptualization of religiosity. American mosaic, 24, 39.
- Küçükcan, T. (2010). Multidimensional Approach to Religion: a way of looking at religious phenomena. Journal for the Study of Religions and Ideologies, 4(10), 60-70.
- Nolan, P., & Lenski, G. E. (2010). Human societies: Introduction to macrosociology. Boulder, CO: Paradigm Publisher.
- L. B. Koenig, M. McGue, R. F. Krueger and T. J. Bouchard, Jr. (2005). Genetic and environmental influences on religiousness: findings for retrospective and current religiousness ratings. Journal of Personality, 73, 471-88
- Gill, Anthony; Erik Lundsgaarde (2004). "State Welfare Spending and Religiosity". Comparative Political Studies 16 (4): 399–436. doi:10.1177/1043463104046694. Free PDF
- Akshat Rathi, New meta-analysis checks the correlation between intelligence and faith, Ars Technica, 11 August 2013.
- Begue, L. (2002). Beliefs in justice and faith in people: just world, religiosity and interpersonal trust. Personality and Individual Differences, 32(3), 375-382.
- Kurst, J., Bjorck, J., & Tan, S. (2000). Causal attributions for uncontrollable negative events. Journal of Psychology and Christianity, 19, 47–60.
|Wikiversity has learning materials about Religiosity|
- Bouchard TJ Jr, McGue M, Lykken D, Tellegen A. Intrinsic and extrinsic religiousness: genetic and environmental influences and personality correlates. Twin Res. 1999 Jun;2(2):88-98.
- Brink, T.L. 1993. Religiosity: measurement. in Survey of Social Science: Psychology, Frank N. Magill, Ed., Pasadena, CA: Salem Press, 1993, pp. 2096–2102.
- Cornwall, M., Albrecht, S.L., Cunningham, P.H., and Pitcher, B.L. 1986. The dimensions of religiosity: A conceptual model with an empirical test. Review of Religious Research, 27:226-244.
- Hill, Peter C. and Hood, Ralph W. Jr. 1999. Measures of Religiosity. Birmingham, Alabama: Religious Education Press. ISBN 0-89135-106-X
- Kirk KM, Eaves LJ, Martin NG. Self-transcendence as a measure of spirituality in a sample of older Australian twins. Twin Res. 1999 Jun;2(2):81-7. PMID 10480742
- Winter T. Kaprio J, Viken RJ, Karvonen S, Rose RJ. Individual differences in adolescent religiosity in Finland: familial effects are modified by sex and region of residence. Twin Res. 1999 Jun;2(2):108-14. PMID 10480745