These terms and their definitions are taken from the 7th edition of the book version of Operation World (2010). Some of the terms below may be defined differently by other organisations; these definitions apply only to how Operation World uses the terms.

10/40 Window The area of the world between latitudes 10° and 40° north of the equator, covering North Africa, Middle East, and Asia. This window contains most of the world’s areas of greatest physical and spiritual need, most of the world’s least-reached peoples and most of the governments that actively oppose Christianity. 

adherent A follower of a particular religion, church or philosophy. This is a broad category based on self-identification rather than a qualitative category of practice and devotion. It includes professing and affiliated adults, and their children (practising and non-practising) who may reside in a given area or country. It refers to those who, if not under coercion, would claim to have a religion even if their adherence is only nominal. 

adult members Adult church members, ages ranging from over 12 to over 18 years (depending on the denomination), who are communicants or full members. Adult members are given in the Members column of statistics in the denominational tables.

affiliated Christians All who are considered as belonging to organized churches. This includes full members, their children, and other participants of the faith community. These figures represent the whole Christian community or inclusive membership. Affiliated Christians are given in the Affiliates statistical column of the denominations table as well as in the Pop % and Affiliates (a total number) statistical columns of the megabloc table.

Affinity Bloc A major grouping of peoples who share a broad range of affinities such as geography, culture, language, history. Examples include Arab, Turkic, Malay. There are 15 Affinity Blocs in the world.  

Ahmaddiya An Islamic revivalist movement that originated in Pakistan, but has now spread to Africa and other continents. It is not considered truly Islamic by orthodox Muslims.

Alpha Course Informal gatherings – in homes, churches, cafes, and a host of other venues – for introducing the gospel to non-Christians. Started in the UK but spread to many countries in the last 15 years. Has proven to be effective in most cultural contexts.

animism Belief that inanimate objects are inhabited by spirits, which must be appeased/placated to avert harm.

born-again believers Those who by grace and through faith in the atoning work of Christ have been regenerated by the Holy Spirit. However, in common usage it often includes those who claim an evangelical conversion experience. The latter is numerable; the former is not.

cargo cults Melanesian Pacific syncretistic religious movements that sprang up during WWII, synthesizing ethnic beliefs and Western materialism.

charismatics Those who testify to a renewing experience of the Holy Spirit and present exercise of the gifts of the Spirit such as glossalalia, healing, prophecy, and miracles. The charismatic renewal, or “Second Wave” Pentecostalism, has generally remained within mainline denominations. A further “Third Wave” renewal movement occurred with many characteristics of the Second Wave, but with less open identification with formal Pentecostalism or the charismatic movement. Second and Third Wave charismatics are counted as a single entity in this book. In our global survey of denominations, we have assessed percentages of affiliated charismatic Christians for each of the 37,500 denominations in the world from 1990-2010. The assessment largely excludes those no longer actively associated with charismatic renewal.

Christian Anyone who professes to be Christian. The term embraces all traditions and confessions of Christianity. It is no indicator of the degree of commitment or theological orthodoxy. The primary emphasis utilized is that of recognizing self-identification as well as accepting the Scriptural principles illustrated in Matt 10:32 and Romans 10:9.

Church (uppercase C). A particular denomination or the universal, invisible Church at a national or worldwide level.

church (lowercase c). A local fellowship of believers. The word is commonly used to mean a church building or church service, but here this usage has largely been avoided. The starting of churches is termed church planting.

creative-access nation A country that limits or forbids the entry of Christian missionaries and for which alternative legal means of entry are required to enable Christians to witness for Christ.

cross-cultural missionaries Full-time Christian workers sent by their churches to work among peoples of a different culture, either cross-culturally within their own nations or abroad.

denomination Any association or network of local congregations linked together, formally or informally, within any given country. Note that international denominations are counted multiple times according to the number of countries in which they have an established presence.

disaffiliated Christians Those who have repudiated their church membership. Appears in both the denomination and the Christian megabloc tables as a negative figure and in italics. This generally occurs only in contexts of large state churches where secularization is strong and where the difference between state church figures and actual self-identification is significant.

doubly affiliated Christians Those who maintain links with two or more denominations at the same time and are claimed as affiliated by both. This appears as an italicized, negative figure in both the denomination and the Christian megabloc tables.

ethnic religions A generic term covering a range of informal religions based on ethnicity, that is, ancestor worship, animism, fetishism, shamanism, spiritism and such.

ethnocultural A people with commonalities of culture, history, customs and a self identity that may be a sub-division of, or transcend, language or ethnicity, e.g. caste groups in India.

ethnolinguistic people An ethnic or racial group speaking its own language. A people distinguished by its self-identity with traditions of common descent, history, customs and language. In this book, a transnational people is counted multiple times according to the number of countries where it has maintained its own ethnolinguistic identity and culture.

ethnoreligionist This is a collective term for adherents of faiths that are usually specifically confined to a particular ethnic group rather than being open or universal. It encompasses (but is not limited to) animists, ancestor-worshippers, polytheists, spirit-worshippers, shamanists, folk religionists, pantheists, cargo cults, tribal messianic movements, and other such expressions of religious belief.

evangelicals All who generally emphasize the following:

The Lord Jesus Christ as the sole source of salvation through faith in Him, as validated by His crucifixion and resurrection.

Personal faith and conversion with regeneration by the Holy Spirit.

Recognition of the inspired Word of God as the ultimate basis and authority for faith and Christian living.

Commitment to biblical witness, evangelism, and mission that brings others to faith in Christ.

Evangelicals are largely Protestant, Independent or Anglican, but some are Catholic or Orthodox. It is one of the Transbloc movements in this book.

This definition is very close but not identical to the definition introduced in David Bebbington’s Evangelicalism in Modern Britain: A History from the 1730s to the 1980s as the Bebbington Quadrilateral, which offered crucicentrism, conversionism, Biblicism, and activism as the four qualities of evangelicalism.

Note: The definition of evangelicals and the statistics relating to them are so fundamental to the contents of this book that it is important for the reader to understand the implications. It enables a measurement of the size and spectacular numerical growth of evangelical Christians over the last few decades.

Evangelicals are here enumerated as:

All affiliated Christians (church members, their children, other participants of the faith community) of denominations that are definitively evangelical in theology as defined above.

The proportion of the affiliated Christians in other denominations (that are not wholly evangelical in theology) who would hold evangelical views, whether Western in origin or otherwise.

This is a theological and not an experiential definition. It does not mean that all evangelicals as defined above are actually born-again. In many nations, only 10-40% of evangelicals so defined may have had a valid conversion and regularly attend church services. However, it does show how many people align themselves with churches where the gospel is being proclaimed as such.

evangelism The activity of Christians spreading the gospel.

evangelization The process of proclaiming the gospel and seeing the outworking of such proclamation. 

evangelized The state of having had the gospel communicated and offered in such a way that the hearer becomes aware of the claims of Christ, and the need to obey and follow Him. Possibly 1.7-1.9 billion people in 2010 fall within this category.

evangelized non-Christian world Non-Christians who have been, or are likely to have been, exposed to the gospel. The equivalent of World B.

fetishist One who attributes magical powers to inanimate objects and depends on amulets, charms or other objects for protection or aggression. Mainly found in Africa and the Americas.

First Wave charismatics are members of classical Pentecostal denominations.

foreign missionaries Full-time Christian workers serving in a country other than their own, sent and commissioned by a church or mission organization to propagate the gospel.

Global North The countries of Europe and North America as well as Australia and New Zealand. This is in contrast to the Global South.

Global South The countries of Latin America and the Caribbean, Africa, Asia, and most of the Pacific. This North/South dichotomy has been increasingly popularized since the late 1990s, but is synonymous (and as equally imperfect as) the West/non-West dichotomy.

gurdwara A Sikh place of worship.

Great Commission The final series of commands of the Lord Jesus Christ before His Ascension – for His followers to evangelize, baptize, disciple, and teach all the peoples of the world.

harvest force The entire body of Christians potentially or actively engaged in Great Commission activity.

home missionaries (or domestic missionaries). Full-time Christian workers serving as missionaries (usually cross-culturally) in their own country, sent and commissioned by a church or mission organization to propagate the gospel.

Independents One of the six major Christian megablocs used in this book. This category includes many of the more recent breakaways from denominations in other megablocs, indigenous denominations not started by foreign missionaries and post-denominational networks.

Least Reached people  See definition of unreached people.

Liberation theology Christian theology redefined on the basis of sociological, and often Marxist, understanding of oppression, thereby motivating the poor to claim equal participation in society.

Majority World The countries in Latin America, Africa, and Asia. This is the term preferred in OW over non-West and Global South.

Marginal One of the six Christian megablocs as defined in this book, comprising marginal or fringe Christian groups. See definition of marginal groups.

marginal groups A general term used in this book to describe all semi-Christian or fringe groups, sects and cults that accept certain Christian features and parts of the Scriptures, together with supplementary revelations claimed to be divine. Most claim that they alone have the “truth”. Many readers may understandably question the validity of including these groups as Christian. However, we consistently classify a person’s religion according to his or her self-assessment. All of these groups claim allegiance to Christ even if their theological understanding of His person, deity, atoning work, or resurrection may be defective. 

Megabloc One of the 6 major groupings of Christian denominations as used in this book. Frequently abbreviated as follows: Protestant P, Independent I, Anglican A, Catholic C (sometimes R), Orthodox O, Marginal M. The categories unaffiliated, disaffiliated and doubly affiliated are not megablocs in themselves, but together with the six megablocs make up the sum total of Christian adherents.

missionary One who is sent with a message. This word of Latin derivation has the same basic meaning as the wider use of the term apostle in the New Testament. Christian missionaries are commissioned by a local church to evangelize, plant churches, and disciple people – away from their home area and often among people of a different race, culture, or language. Modern usage varies widely with strong regional preferences:

The stricter North American usage – all sent to evangelize, plant churches or minister outside their homelands.

The wider European and Latin American usage – all sent to evangelize, plant churches or minister cross-culturally, whether in other lands or in their homelands.

The even broader African and Asian usage, which is closer to the biblical concept indicated above and which encompasses all those sent to evangelize, plant churches and minister away from their home areas, whether cross-culturally or not and whether in their own countries or abroad. However, such breadth in the use of missionary makes it difficult for the researcher to specify the cultural or geographical distance a Christian worker must cover in order to be properly categorized as a missionary (as contrasted with an evangelist). It is especially helpful in such a case to be able to identify the subdivision of missionaries working within their own or a near culture.

In this book we have sought to synthesize differing perspectives in dividing all missionaries of each country and region into the three categories of foreign, cross-cultural and home/domestic. Most, but not all, foreign missionaries are cross-cultural, for some are actually working within expatriate communities of their own culture. 

Nearly every country is a “missionary-sending” country. What used to happen “from the West to the rest” is now an extensive and expanding global activity. Missionary vision is alive even in those countries where the Church is young, small, or under persecution. When praying for those many places in the world that need more missionaries, pray with an awareness that the answer may come from east, west, north, or south, from a neighbouring culture or one on the other side of the world.

For purposes of Operation World, the term missionary is defined as meeting the following criteria:

  • Self-identification as a missionary and serving in the ministry context out of a deliberate sense of spiritual calling and Kingdom purpose.
  • Commissioning and recognition as a missionary by home church and sending agency.
  • Term of service of at least two years.
  • Serving Christ outside of their home context – this usually but not exclusively implies serving abroad/outside their home region, and across cultural boundaries.
  • When not cross-cultural, work is occurring in an unevangelized context where the Church has not been established.

non-Western world The countries of Latin America, Africa and Asia. Previously, it was common to use Third World or Two-Thirds World to describe these countries. These terms are now obsolete, since the collapse of the Communist Second World. Synonymous with Global South and Majority World.

Pentecostals Those affiliated to specifically Pentecostal denominations committed to a Pentecostal theology, usually including a post-conversion experience of a baptism in the Spirit, present exercise of the gifts of the Spirit and speaking in tongues.

people cluster A grouping of ethnolinguistic peoples with commonalities of a shared identity, language, culture, history, and often a common name. Usually transnational.

people group A significantly large sociological grouping of individuals who perceive themselves to have a common affinity. From the viewpoint of evangelization, this is the largest possible group within which the gospel can be spread without encountering barriers of understanding or acceptance. There are basically three types:

Ethnolinguistic people group, which defines a person’s identity and primary loyalty according to language and/or ethnicity. This is the category emphasized in this book. We have reserved the word people rather than people group for this type. Cross-cultural church-planting teams of missionaries are needed for peoples in this category. According to the Joshua Project, there are 10,340, if national boundaries are ignored, 16,350 if the same people are counted separately for each country. 

Sociological people group – a grouping defined by its long-term relation to the rest of society, such as by migration or traditional occupation or class, but not having a self-contained culture or identity as an ethnic group. In most cases, local church outreach is required – either to plant daughter churches or to incorporate converts into multi-social congregations. There are probably hundreds of thousands of such people groups.

Incidental people groups – casual associations of individuals that may be temporary and are usually the result of circumstances rather than personal choice. Examples of such groups are high-rise flat dwellers, drug addicts, occupational groupings, commuters, and such. These groupings present unique problems and opportunities for evangelism, but only rarely is it appropriate for specific churches to be planted for the sole benefit of such groups.

people movement A movement of a large number of non-Christians in a particular people into the Church. This is frequently a group decision. It presents a wonderful opportunity to win and disciple many for the Lord by leading them into a personal faith in the Lord Jesus Christ. Failure to do so can soon lead to nominalism or syncretism.

polytheism Belief in many gods.

post-charismatics Those once involved but no longer engaged in charismatic movements. This is not necessarily a theological decision or a rejection of the Holy Spirit’s active presence in believers’ lives so much as disillusionment with the charismatic Church sub-culture and excess that occurred in the West in the 1990s and 2000s.

professing A claim of allegiance to a religious belief – whether known to, or listed in the records of, an organized religion. Professing Christians usually number more than affiliated Christians. Where the difference is significant, a figure for unaffiliated Christians is added to the megabloc table in the country section. Professing = (affiliated + unaffiliated) – (doubly affiliated + disaffiliated).

reached/unreached A term widely used today to describe people groups and areas that have or have not responded to the preaching of the gospel. Use of the term has been continued in this book despite the faultiness of the terminology. Strictly, it should be a measure of the exposure of a people group to the gospel, not a measure of the response.

renewal A quickening or enlivening of personal commitment to Christ in the churches. Charismatic renewal in the historic denominations is an example. See definition of charismatics above.

Renewalist A term increasingly used to describe Christians who adhere to either Pentecostal or charismatic theology and practice.

restricted-access nations States that limit or prevent Christian ministry by expatriates as missionaries. Alternatively they are called creative-access nations, where expatriates must seek secular avenues of entry – business, medical work, teaching, as house servants or other means. Most countries in this category have been Communist or Muslim, but today are predominantly Muslim.

revival The restoring to life of believers and churches that have previously experienced the regenerating power of the Holy Spirit but have become cold, worldly and ineffective. Often wrongly used of evangelistic campaigns, revival really signifies a sovereign act of God as an answer to prayer in bringing about a spiritual awakening and outpouring of the Holy Spirit on His people.

Second Wave charismatics Christians who have experienced renewal within mainline non-Pentecostal denominations.

shamanism Traditional ethnic religious belief centred on a hierarchy of healers and soothsayers. A term used primarily in Asia.

sharia The Islamic body of law based on the Qur’an and tradition (hadith).

Shia Muslims Followers of Ali, the cousin of Mohammed. The second-largest branch of Islam. Strong in Iran, Central and South Asia.

short-term worker (STW) A missionary serving for a period of 6 months to 2 years.

Sufi A practitioner of Sufism, which focuses on the esoteric, ecstatic, mystical, and internal aspects of Islam. 

Sunni Muslims Followers of the main branch of Islam.

syncretism The attempt to synthesize elements of different religious systems into a single body of belief and practice. Baha’i, for instance, is a synthesis of Islamic, Christian, and other religious tenets. Some African Initiated Churches have sought to synthesize elements of Christianity with pre-Christian traditional beliefs.

Third Wave charismatics Christians in newer charismatic denominations or post-denominational networks.

Traditional ethnic A generic term used in the Religions table to cover all the informal and ethnic religions in a country.

transbloc movement A term used to cover evangelicals, charismatics, and Pentecostals in this book. Each of these is found in some or most of the six Christian megablocs.

unaffiliated Christians Those who profess to be Christian but who are not associated with any formal church denomination or group.

unevangelized  Those who have had no adequate opportunity to hear the gospel or respond to it.

Universalism The belief that ultimately all people will be saved irrespective of religious belief or lack of it while on earth. The underlying premises are that many have an implicit awareness of a supernatural being to which they respond by doing good to others and that a loving God could not consign people to eternal punishment for sin – rejected by most evangelicals as non-biblical teaching.

unreached people An ethnolinguistic people among whom there is no viable indigenous community of believing Christians with adequate numbers and resources to evangelize their own people without outside (cross-cultural) assistance. At times, the terms least reached people, hidden people, or frontier people group are used.

Wahhabi A conservative, fundamentalist Muslim sect. Largely in Saudi Arabia, Gulf States, and Central Asia.

Western World The countries of Europe, North America, and Australia.

World A Nations and peoples in the least evangelized world. Those nations and peoples that are less than 50% evangelized as defined in the World Christian Encyclopaedia and World Christian Database.

World B Nations and peoples in the evangelized non-Christian world. Defined as those nations and peoples that are more than 50% evangelized, but less than 60% Christian (including all major Christian groups).

World C Nations and peoples in the Christian world. Defined as those nations and peoples that are more than 60% professing Christian. This includes all nominal and affiliated Christians of all ecclesiological traditions and not only Protestants.

Yezidi/Yazidi A syncretistic religion in Iraq, Turkey and the Caucasus based on Zoroastrian, Jewish, Nestorian, Christian, and Muslim beliefs. Largely among Kurds.

Content taken or adapted from Operation World, 7th Edition (2010) and Pray for the World (2015). Both books are published by InterVarsity Press. All rights reserved.