The Baháʼí Faith formed in the mid-19th century in Iran, later gaining converts in India, East Africa, and the Western world. The Bahá'í Faith is established in more than 100,000 localities in virtually every country and territory around the world. Traveling promoters of the religion played a significant role in spreading the religion into most countries and territories during the second half of the 20th century, mostly seeded out of North America by the planned migration of individuals. The Baháʼí Faith was recognized as having a widespread international membership by the 1980s. Author Denis MacEoin asserted in 2000 that Baháʼí Faith was the second-most geographically widespread religion after Christianity.
The Baháʼí World Centre estimated over a million Bahá'ís in 1965, 5 million in 1991, and about 8 million in 2020. The official agencies of the religion have focused on publishing data such as numbers of local and national spiritual assemblies, countries and territories represented, languages and tribes represented, schools, and publishing trusts, not the total number of believers.
Analyzing Baháʼí data on localities and activity levels, Danish sociologist Margit Warburg suggested that by 2001, registered Baháʼís reliably numbered over 5 million. Other independent estimates, such as Encyclopædia Britannica in 2010, and the World Christian Encyclopedia in 2001, listed Baháʼís and sympathizers as over 7 million. The Baháʼí Faith was described in 2013 as the fastest growing religion by percentage across the 20th century.
The number of Baháʼí adherents is difficult to estimate accurately. Few national Baháʼí communities have the administrative capacity to enumerate their members and Baháʼí membership data does not break out active participation from the total number of people who have expressed their belief. Due to its small size, few censuses or religious surveys include the Baháʼí Faith as a separate category and some government censuses count Baháʼís as Muslims or Hindus. Country-level detail from the World Christian Encyclopedia (WCE), on which many estimates rely, counts declared Baháʼís along with sympathizers, leading to much higher counts than those of self-identifying Baháʼís.
Difficulties in enumeration
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. In the Middle East, especially Iran, Baháʼís face persecution, and the lack of Baháʼí administration makes it difficult to maintain a count.
Baháʼí authors Peter Smith and Moojan Momen, commenting on the difficulties of counting Baháʼís, wrote the following:
Definition of membership Throughout the early development of the Baháʼí Faith in Iran and the West, Baháʼís often retained some of the religious identity that they converted from, many remaining members of churches and mosques. Later, Shoghi Effendi made it clear that the Baháʼí Faith was its own tradition with laws and institutions, and that Baháʼís could not remain members of other religions. The practice of maintaining membership rolls of believers began in the 1920s.
In the 1930s the Baháʼís of the United States and Canada began requiring new adherents to sign a declaration of faith, stating their belief in Baháʼu'lláh, the Báb, and ʻAbdu'l-Bahá, and affirming that there are laws and institutions to obey. The original purpose of signing a declaration card was to allow followers to apply for lawful exemption from active military service. The signature of a card later became optional in Canada, but in the US is still used for records and administrative requirements.
All local and national Spiritual Assemblies are expected to keep membership records that include declarations of faith and withdrawals, which are used for annual assembly elections. The Baháʼí system of membership thus has a system of contracting into the religion and some maintenance of the membership list is required for community functioning. Being removed from membership requires an opposite declaration of disbelief.
Children 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. Early membership rolls excluded children of Baháʼís and didn't even count them separately. In 1979 the Universal House of Justice requested that children be included separately for statistical purposes, matching the methodology of most censuses and surveys. Before that, membership rolls may have only indicated ages 21 or older (the age required for voting).
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.
Active vs inactive
Another difficulty arises from defining membership based on participation. The number of active participants in any religious movement will always be smaller than the number who profess belief. The prevailing norm in the Western world is that members of minority religious groups must be actively participating to be considered a member, and members of majority religious groups have a large number of passive adherents. Margit Warburg wrote,
Warburg also noted: "Baháʼís do not lose membership status just by being inactive."
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. For example, in its 2020 Annual Report the US National Spiritual Assembly had 177,647 registered Baháʼís of all ages, only 77,290 of which had good addresses, and 57,341 total participants in core activities, with 37% of attendees from outside of the Baháʼí population. The higher American number has been challenged because it includes some who no longer believe, but the lower number with good addresses does not include inactive Baháʼís who continue their belief. As author William Garlington noted,
Using activity data, Warburg estimated a percentage of activity in Baháʼí communities around the world and concluded that in 2001 there were reliably 5.1 million registered Baháʼís in the world and 900,000 active Baháʼís, or 18% of the total. The estimates on activity were broken out by continent: Europe 82% active, USA and Canada 71%, Australia and New Zealand 91%, Africa 22%, India 5%, Other Asia 26%, Latin America 13%, and Oceania 43%. On the question of whether the Baháʼí numbers are intentionally inflated, Warburg feels that the "numbers are not rooted in any sinister manipulation of data".
Number of Baháʼís worldwide Baháʼí sources In 2020, the Secretariat of the Universal House of Justice wrote, "on the basis of information received from Baháʼí communities across the world, and on reputable external sources", the current estimate for the number of Baháʼís worldwide is "about eight million", and Baháʼís reside in "well over 100,000 localities". A 1997 statement by the NSA of South Africa wrote: "…the Baháʼí Faith enjoys a world-wide following in excess of six million people." As early as 1991 official estimates were of "more than five million Baháʼís", which was still in use as of 2020. In 1989, the journal Religion published an article by Baháʼí authors Moojan Momen and Peter Smith. They observed that in the 1950s there were "probably in the region of 200,000 Baháʼís world-wide. The vast majority of these (over 90%) lived in Iran. There were probably fewer than 10,000 Baháʼís in the West and no more than 3,000 Baháʼís in the Third World, mostly India". By the end of the 1960s, they wrote, "we 'guestimate' that there may now have been about one million Baháʼís." And by 1988 they estimated about 4.5 million. A 1987 report, published in the United States Baháʼí News reported 3.62 million Baháʼís in 1979 and 4.74 million Baháʼís in 1986, a growth of 31% over the period, or 4.4% per year on average. The document The Promise of World Peace, produced by the Universal House of Justice in 1985, stated that the Bahá’í community has "some three to four million people". Baháʼí author Moojan Momen wrote in 2008, "In the early 1950s, there were probably some 200,000 Baháʼís in the world. This has increased to about a million by the late 1960s, about four and a half million by the late 1980s, and over five million by 2000s." The first known survey of the religion comes from an unpublished work in 1919–1920 gathered by John Esslemont and had been intended to be part of his well-known Baháʼu'lláh and the New Era. In it, consulting various individuals, he summarizes the religion's presence in Egypt, Germany, India, Iran, Iraq, Turkestan, and the United States. It did not arrive at a total but did have some regional statistics based on some individual reports. In 1867, 53 Baháʼís from Baghdad sent an appeal to the American Consul in Beirut for assistance in freeing Bahá'u'lláh from Ottoman captivity. According to missionary Henry Harris Jessup, "The petitioners claim that they number 40,000."
Other sources 2010s and newer In 2020, the World Religion Database has estimated a worldwide Baháʼí population of 8,531,050. In 2017, The Economist reported that there were more than 7 million Baháʼís in the world. In 2016, the book 12 Major World Religions wrote, "Today it numbers at least 5 million adherents and possibly more." In 2015, the Yearbook of International Religious Demography noted just over 7.8 million Baháʼís in the world, having grown at an overall rate of 2.79% across the century 1910 to 2010. The 10 countries with the largest Baháʼí populations were: India, United States, Kenya, Vietnam, DR Congo, Philippines, Zambia, South Africa, Iran and Bolivia, ranging from 232,000 to just over 2,000,000 in India. In 2013, the book The World's Religions in Figures: An Introduction to International Religious Demography wrote, "The Baha'i Faith is the only religion to have grown faster in every United Nations region over the past 100 years than the general population; Bahaʼi was thus the fastest-growing religion between 1910 and 2010, growing at least twice as fast as the population of almost every UN region." In 2011, Bei Dawei said in an academic conference presentation that the Baháʼí Faith had "several hundred thousand" adherents. He noted that "estimates of five, six, or seven million are more usually encountered" but said that these estimates are projections based on self-reporting by Baháʼís and that the national figures they are based on "tend to exceed apparent Bahá'í activity by whole orders of magnitude." In 2010, The World Religion Database stated that there were 7.3 million Baháʼís in the world. The Association of Religion Data Archives cited this estimate. Encyclopædia Britannica also estimated a total of 7.3 million Baháʼís residing in 221 countries. Religions of the World: A Comprehensive Encyclopedia of Beliefs and Practices estimated 7.4 million Baháʼís, citing UN median variant figures from World Population Prospects: The 2006 Revision.
2000s In 2009, Paula Hartz wrote in World Religions: Baha'i Faith: "Today the Baha’i Faith has some 5 million followers. It is one of the world’s fastest-growing religions. It is also probably the most diverse." In 2007, The World Factbook states that Baháʼís make up 0.12% of the world, corresponding to 7.9 million people. In 2006, Margit Warburg's academic book on the Baháʼí Faith claimed, "a conservative estimate would be that in 2001 there were about 5.1 million registered Baháʼís in the world."