Polls and surveys Decades of anthropological, sociological, and psychological research have shown that congruence between an individual's beliefs, attitudes, and behavior concerning religion and irreligion is rare. The reliability of any poll results, in general and specifically on religion, can be questioned due numerous factors such as: • there have been very low response rates for polls since the 1990s • polls consistently fail to predict government election outcomes, which signifies that polls in general do not capture the actual views of the population • biases in wording or topic affect how people respond to polls • polls categorize people based on limited choices • polls often generalize broadly • polls have shallow or superficial choices, which complicate expressing people's complex religious beliefs and practices • interviewer and respondent fatigue is very common Researchers also note that an estimated 20–40% of the population changes their self-reported religious affiliation/identity over time due to numerous factors and that usually it is their answers on surveys that change, not necessarily their religious practices or beliefs. In general, polling numbers are difficult to interpret and should not be taken at face value, since people in different cultural contexts may interpret the same questions differently. Responses to Gallup polls on religiosity vary based on how the question is worded. Since the early 2000s, Gallup has routinely asked about complex topics like belief in God using three different question wordings and they have consistently received three different percentages in the responses.
In the United States Two major surveys in the United States, the
General Social Survey (GSS) and the Cooperative Congressional Election Study (CCES), have consistently produced discrepancies between their demographic estimates on religion that amount to 8% and growing. This is due to a few factors, such as differences in question wording that impact participant responses due to "social desirability bias"; the lumping of very different groups (atheist, agnostics, nothing in particular) into singular categories (e.g., "no religion" vs "nothing in particular"); and differences in the
representativeness of the samples (e.g., "nones" are more politically moderate in the GSS sample than in the CCES sample, while Protestants are more conservative in the CCES sample than in the GSS sample). The 2008
American Religious Identification Survey (ARIS) found a difference between how people identify and what people believe. While only 0.7% of U.S. adults identified as atheist, 2.3% said there is no such thing as a god. Only 0.9% identified as agnostic, but 10.0% said there is either no way to know if a god exists or they weren't sure. Another 12.1% said there is a higher power but no personal god. In total, only 15.0% identified as Nones or No Religion, but 24.4% did not believe in the traditional concept of a personal god. The conductors of the study concluded, "The historic reluctance of Americans to self-identify in this manner or use these terms seems to have diminished. Nevertheless ... the level of under-reporting of these theological labels is still significant ... many millions do not subscribe fully to the theology of the groups with which they identify." According to a
Pew Research Center study in 2009, only 5% of the total US population did not have a belief in a god. Out of all those without a belief in a god, only 24% self-identified as "atheist", while 15% self-identified as "agnostic", 35% self-identified as "nothing in particular", and 24% identified with a religious tradition.
Gallup's editor-in-chief, Frank Newport, argues that numbers on surveys may give an incomplete picture. In his view, declines in religious affiliation or belief in God on surveys may not actually reflect real declines, but instead increased honesty to interviewers on spiritual matters due to viewpoints previously seen as deviant becoming more socially acceptable.
Censuses Questions of religion are "marginal" in censuses, usually optional, and are left out of most censuses in most countries. Despite attempts to standardize wording, census phrasing of the religion question have not been consistent over time or from country to country, with responders understanding them in 3 different ways. In the Czech Republic, one of the most secular countries in the world, religious affiliation is optional in the census and in 2011 almost half the population (44%) did not answer the question; obscuring the actual number of religious and nonreligious people in the country. ==Causes and correlates==