This is a highly disparate group. Most current estimates of the numbers of people identifying themselves as secular, non-religious, agnostic or atheist are between 800 and 1 billion people, but the figure could be as high as 20% of the world population, or about 1.2 billion: “Over 20 percent of the world’s population does not claim any allegiance to a religion. Most are agnostics… others are atheists who deny the existence of God.” But such a high figure is difficult to support and perhaps reflects Communist-era official government statistics. Prior to Communist takeovers and government attempts to eradicate religion, countries such as China and Russia had very high levels of affiliation with organized religions, particularly Islam, Christianity, Buddhism and Taoism, as well as high levels of participation in and belief in traditional local traditions such as shamanism, ancestor worship and spiritism. Since the fall of Communism in former Soviet nations and the relaxation of anti-religious policies in China, religious affiliation and activity, particularly in Christianity, Buddhism and Islam has increased dramatically.
People who specify atheism as their religious preference actually make up less than one-half of one percent of the population in many countries where much larger numbers claim no religious preference, such as theUnited StatesandAustralia.
One portion of this broad grouping includes those who describe themselves as “non-religious,” in other words, those who don’t belong to an organized religion. This group may or may not contemplate philosophical and spiritual matters and may or may not be involved in a religious, faith or philosophical community. “Non-religious” is not equated with non-belief in God or a Higher Power, as many people in this category expressly do have this belief.
The use of the term “non-religious” or “secular” can refer to belief, or participation in systems which are not traditionally labeled “religions”. However, in the absence of traditional religions, society may exhibit the same behavioral, social and psychological phenomena associated with religious cultures but in association with secular, political, ethnic, commercial or other activities. Marxism and Maoism, for instance, had their scriptures, authority, symbolism, liturgy, clergy, prophets, proselytizing and etc. Sports, art, patriotism, music, drugs, mass media and social causes have all been observed to fulfill roles similar to religion in the lives of individuals, capturing the imagination and serving as a source of values, beliefs and social interaction.
In a broader sense, sociologists point out that there are no truly “secular societies,” and that the word “non-religious” is a misnomer. Sociologically speaking, “non-religious” people are simply those who derive their worldview and value system primarily from alternative, secular, cultural or otherwise non-revealed systems rather than traditional religious systems. Like traditional religions, secular systems (such as Communism, Platonism, Freudian and Jungian psychology, Nazism, pantheism, atheism or nationalism) typically have favored spokespeople and claim to present a universally valid and applicable “truth”.
This group also includes more proactive or well-defined philosophies such as secular humanism, atheism, agnosticism, deism, pantheism and freethought, most of which can be classified as religions in the sociological sense, albeit secular religions.
In the Western world, Europe has the most self-avowed non-religious, atheists and agnostics (41 million) with the numbers particularly high in Scandinavia. The self-described non-religious segment of society in Australia and New Zealand is also high, at around 15%.
 (O’Brien, Joanne and Palmer, Martin, The State of Religion Atlas, Simon & Schuster: New York, 1993, p 41.)