Agnosticism is the view or belief that the existence of God, of the divine or the supernatural is unknown or unknowable. Another definition provided is the view that "human reason is incapable of providing sufficient rational grounds to justify either the belief that God exists or the belief that God does not exist."
Irreligion is the neglect or active rejection of religion and, depending on the definition, a simple absence of religion.
The Oxford English Dictionary defines religiosity as: "Religiousness; religious feeling or belief. [...] Affected or excessive religiousness". Different scholars have seen this concept as broadly about religious orientations and degrees of involvement or commitment. Religiosity is measured at the levels of individuals or groups and there is a lack of agreement on what criteria would constitute religiosity among scholars. Sociologists of religion have observed that an individual's experience, beliefs, sense of belonging, and behavior often are not congruent with their actual religious behavior, since there is much diversity in how one can be religious or not. Multiple problems exist in measuring religiosity. For instance, measures of variables such as church attendance produce different results when different methods are used - such as traditional surveys vs time-use surveys.
The study of religiosity and intelligence explores the link between religiosity and intelligence or educational level. Religiosity and intelligence are both complex topics that include diverse variables, and the interactions among those variables are not always well understood. For instance, intelligence is often defined differently by different researchers; also, all scores from intelligence tests are only estimates of intelligence, because one cannot achieve concrete measurements of intelligence due to the concept’s abstract nature. Religiosity is also complex, in that it involves wide variations of interactions of religious beliefs, practices, behaviors, and affiliations, across a diverse array of cultures.
Religion has been a major influence on the societies, cultures, traditions, philosophies, artistic expressions and laws within present-day Europe. The largest religion in Europe is Christianity. However, irreligion and practical secularisation are also prominent in some countries. In Southeastern Europe, three countries have Muslim majorities, with Christianity being the second-largest religion in those countries. Ancient European religions included veneration for deities such as Zeus. Modern revival movements of these religions include Heathenism, Rodnovery, Romuva, Druidry, Wicca, and others. Smaller religions include Indian religions, Judaism, and some East Asian religions, which are found in their largest groups in Britain, France, and Kalmykia.
Some movements or sects within traditionally monotheistic or polytheistic religions recognize that it is possible to practice religious faith, spirituality and adherence to tenets without a belief in deities. People with what would be considered religious or spiritual belief in a supernatural controlling power are defined by some as adherents to a religion; the argument that atheism is a religion has been described as a contradiction in terms.
Accurate demographics of atheism are difficult to obtain since conceptions of atheism vary considerably across different cultures and languages, ranging from an active concept to being unimportant or not developed. Also in some countries and regions atheism carries a strong stigma, making it harder to count atheists in these countries. In global studies, the number of people without a religion is usually higher than the number of people without a belief in a deity and the number of people who agree with statements on lacking a belief in a deity is usually higher than the number of people who self-identify as "atheists".
Atheism, in the broadest sense, is an absence of belief in the existence of deities. Less broadly, atheism is a rejection of the belief that any deities exist. In an even narrower sense, atheism is specifically the position that there are no deities. Atheism is contrasted with theism, which in its most general form is the belief that at least one deity exists.
Atheism, agnosticism, scepticism, freethought, secular humanism or general irreligion are increasing in Australia. Post-war Australia has become a highly secularised country. Religion does not play a major role in the lives of much of the population.
In the United States, between 6% and 21% of citizens demonstrated nonreligious attitudes and naturalistic worldviews, namely atheists or agnostics. The number of self-identified atheists and agnostics was around 4% each, while many persons formally affiliated with a religion are likewise non-believing.
According to sociologists as of 2022, "the proportion of atheists in the US has held steady at 3% to 4% for more than 80 years." According to the Pew Research Center in a 2014 survey, self-identified atheists make up 3.1% of the US population, even though 9% of Americans agreed with the statement "Do not believe in God" while 2% agreed with the statement "Do not know if they believe in God". Other polling by Gallup in 2022 showed that 17% of respondents replied "No" when asked "Do you believe in God?", and another from 2023 found that 12% of respondents replied they "Do not believe in" God with 14% replying they were "Not sure about" the existence of God. Regardless of question or polling service, there is evidence the number of people not believing in God is increasing.
Agnostic atheism or atheistic agnosticism is a philosophical position that encompasses both atheism and agnosticism. Agnostic atheists are atheistic because they do not hold a belief in the existence of any deity and are agnostic because they claim that the existence of a divine entity or entities is either unknowable in principle or currently unknown in fact.
Irreligion in Estonia pertains to atheism, agnosticism, and secularism of the people and institutions of Estonia. Irreligion is prominent in Estonia, where a majority of citizens are unaffiliated with any religion. Estonian irreligion dates back to the 19th century, when Estonian nationalists and intellectuals deemed Christianity a foreign religion in opposition to Estonian independence. Irreligion in Estonia was later accelerated by the Soviet occupation of the Baltic states, in which state atheism was enforced. By some metrics, Estonia is the most irreligious country in the world.
Irreligion in Ireland pertains to the population of Ireland that are atheist, agnostic, or otherwise unaffiliated with any religion. The 2022 census recorded that 14% of the population was irreligious; the second largest category after Roman Catholicism. The population was traditionally devoutly Catholic throughout much of Ireland's modern history, with a peak of 94.9% identifying as Catholic in the 1961 census. This percentage has declined to 69% in the 2022 census, the lowest recorded. Conversely, those with no religion made up less than 0.1% of the population in 1961; the proportion grew slowly until the 1991 census where it began to rapidly increase to its current share of 14% of the population in 2022.
The relationship between the level of religiosity and the level of education has been studied since the second half of the 20th century.
China has the world's largest irreligious population, and the Chinese government and the ruling Chinese Communist Party (CCP) are officially atheist. Despite limitations on certain forms of religious expression and assembly, religion is not banned, and religious freedom is nominally protected under the Chinese constitution. Among the general Chinese population, there are a wide variety of religious practices. The Chinese government's attitude to religion is one of skepticism and non-promotion.
Irreligion in Latin America refers to various types of irreligion, including atheism, agnosticism, deism, secular humanism, secularism and non-religious. According to a Pew Research Center survey from 2014, 8% of the population is not affiliated with a religion.
Atheism in the African diaspora is atheism as it is experienced by black people outside of Africa. In the United States, black people are less likely than any other ethnic groups to be religiously unaffiliated, let alone identifying as atheist. The demographics are similar in the United Kingdom. Atheists are individuals who do not hold a belief in God or gods. Atheism is a disbelief in God or gods or a denial of God or gods, or it is simply a lack of belief in gods. Some, but not all, atheists identify as secular humanists, who are individuals who believe that life has meaning and joy without the need for the supernatural or religion and that all individuals should live ethical lives which can provide for the greater good of humanity. Black atheists and secular humanists exist today and in history, though many were not always vocal in their beliefs or lack of belief.
Irreligion in Romania is rare. Romania is one of the most religious countries in Europe, with 92% of people saying that they believe in God. Levels of Irreligion are much lower than in most other European countries and are among the lowest in the world. At the 2011 census, only 0.11% of the population declared itself atheist, up from the 2002 census, while 0.10% do not belong to any religion. While still one of the most religious countries in Europe, practicing, church and mass attendance is quite low, even compared to some less religious countries than Romania. It is mainly practiced by elderly people, mainly in rural areas, while in urban areas church attendance and practice is much lower. As of 2021, almost 85% are declared religious, of which about 73% are declared orthodox, 12% other religions, about 1% atheists or irreligious and about 14% declared nothing about religion.
Irreligion in Italy includes all citizens of Italy that are atheist, agnostic, or otherwise irreligious. Approximately 12% of Italians are irreligious, and no affiliation is the second most common religious demographic in Italy after Christianity. Freedom of religion in Italy was guaranteed by the Constitution of Italy following its enactment in 1948. Until then, the Catholic Church was the official state church of Italy.
