'Nontheism' is a term that describes anyone who is not a theist. In other words, a nontheist is anyone who does not have a specific belief in a god or deity. It usually refers to anyone who does not have any religiousbelief. This is a lot like atheism, but the two terms are often used in different ways.
Origin of the term
The term "nontheism" was first used by G. J. Holyoake in 1852. He used it because of the bad associations with the term atheism.
"Mr. [Charles] Southwell has taken an objection to the term Atheism. We are glad he has. We have disused it a long time [...]. We disuse it, because Atheist is a worn-out word. Both the ancients and the moderns have understood by it one without God, and also without morality. Thus the term connotes more than any well-informed and earnest person accepting it ever included in it; that is, the word carries with it associations of immorality, which have been repudiated by the Atheist as seriously as by the Christian. Non-theism is a term less open to the same misunderstanding, as it implies the simple non-acceptance of the Theist's explanation of the origin and government of the world."
Nontheism in society
Today, about 2.3% of the world's population describes itself as atheist. About 11.9% is described as 'nontheist'. Between 64% and 65% of Japanese describe themselves as atheists, agnostics, or non-believers, and up to 48% in Russia. The percentage of such people in European Union member states ranges between 6% (Italy) and 85% (Sweden).
2.3% Atheists: Persons professing atheism, skepticism, disbelief, or irreligion, including the militantly antireligious (opposed to all religion).
11.9% Nonreligious: Persons professing no religion, nonbelievers, agnostics, freethinkers, uninterested, or dereligionized secularists indifferent to all religion but not militantly so.
↑However, data from the U.S. State Dept. may contradict this figure, since 44% are reported as adherents of Shinto, a polytheistic religion, and information was not provided on the number of respondents identifying with multiple categories. (64% atheists/agnostics/non-believers, plus 44% Shintoists, adds up to more than 100%.)