Baháʼí Faith by country

[3][4] Author Denis MacEoin asserted in 2000 that Baháʼí Faith was the second-most geographically widespread religion after Christianity.

[11] Other independent estimates, such as Encyclopædia Britannica in 2010,[12] and the World Christian Encyclopedia in 2001,[13] listed Baháʼís and sympathizers[a] as over 7 million.

[19][20] The fact that the religion is diffuse and proportionally small is a major barrier to demographic research by outsiders.

Even in the United States, where significant resources are dedicated to gathering data, the Baháʼí Faith is often omitted from religious surveys due to the high sample size required to reduce the margin of error.

Baháʼí authors Peter Smith and Moojan Momen, commenting on the difficulties of counting Baháʼís, wrote the following: With any religious movement there are invariable problems of quantification unless the movement's own enumeration techniques are exceptionally efficient, or government censuses incorporate questions on religion.

The original purpose of signing a declaration card was to allow followers to apply for lawful exemption from active military service.

[citation needed][26] A peculiar difficulty arises in counting Baháʼís because a tenet of the faith is that parents cannot choose the religion of their children and that 15 is the age of spiritual maturity when an individual can make the choice.

[21] In 1979 the Universal House of Justice requested that children be included separately for statistical purposes, matching the methodology of most censuses and surveys.

[28] The change toward including children in statistics caused an increase in the total number of reported Baháʼís in the late 1980s, but has been consistent since.

"[29] In the 1980s the Baháʼís of the United States started including “address unknown” in their membership statistics; members designated as such may profess belief but are no longer participating in community life.

[32] As author William Garlington noted, Just as there are many people who claim to be followers of Jesus Christ and yet are not official members of an established church, it seems fair to assume that there are a sizable number of individuals who identify with Baha'u'llah and his principles while remaining outside the established institutions of the Baha'i Faith... the significant point is that at least [the registered Baha'is] have experienced enough identity with the Baha'i teachings to have made official written declarations of that belief.

[29] "The movement has had remarkable success in establishing itself as a vigorous contender in the mission fields of Africa, India, parts of South America, and the Pacific, thus outstripping other new religions in a world-wide membership of perhaps 4 million and an international spread recently described as second only to that of Christianity.

"[5]During ʻAbdu'l-Bahá's tour of North America, several newspapers made claims of how large the religion was, with figures in the range of millions of people: Although the Baháʼí News Service has reported on the total number of Baháʼís in the world, the data is not broken out by country.