Data source: Gina A. Zurlo and Todd M. Johnson, eds., World Christian Database (Leiden/Boston: Brill, 2025).
| Glossary item | Definition |
|---|---|
| Indo-Iranian | One of the 13 ethnic regions of mankind, with over 230 languages. |
| Indo-Malay | An Asian ethnolinguistic family, with 300 languages. |
| Indonesian indigenous churches | Denominations indigenous to, and started by, Indonesians. |
| industrial mission | A Christian approach to industrial organizations in a particular region. |
| industrialization | The act or process of becoming industrial in a particular region or country. |
| ineligible member | An adult church member who is not eligible to take communion, usually being under discipline for some offense. |
| infant baptism | In Catholic, Orthodox, Anglican, Lutheran, Methodist, Reformed and other pedobaptist (qv) traditions, the administration of baptism to children under 5 years old. |
| infants | Defined here as those under 5 years old, or the preschool population, including new-born babies; although the term is often restricted to children who have not reached their first birthday. |
| infants | Children or babies under 5 years old; the preschool population. |
| infilling by the Holy Spirit | Persons baptized in the Spirit each year are enumerated in the statistics of several Pentecostal denominations (e.g. Assemblies of God, US). |
| inflation | Annual percentage growth in consumer prices, as measured by the consumer price index (qv). |
| infobasing | Use of a large collection of useful, understandable, and easily retrieved information stored in a computer. Information is more useful than raw data (facts and figures) but less organized than knowledge (understanding, learning) or wisdom (superior understanding). |
| informant | A respondent (qv) in a census or survey; a person supplying information. |
| inhabitant | A person who dwells or resides permanently in a place as distinguished from a transient lodger or visitor, or a resident (who may be temporary or short-term). |
| Injerto | The issue of a Latin American White and a Chinese or Japanese. |
| inner language | Alternative term for a language (qv) as utilized in this WCE/WCT/WCD survey. |
| inner lingua franca | A common language with over 100,000 non-native speakers, and strictly defined as a language (inner language) in the World Language Classification. |
| inner-city ministry | The parish ministry adapted to innercity dwellers in areas of urban blight. |
| inquirers | See enquirers. |
| inscriptions | A technical term in Bible correspondence course ministry for enrolments or the number of persons signing on, enrolling or writing in. |
| inspectorate | (French, inspection). In French Lutheran usage, a large area of ecclesiastical jurisdiction equivalent to a deanery or presbytery. |
| institutes, religious | See religious institutes. |
| institutional population | Persons in correctional schools, hospitals, prisons and other institutions, who are often separately enumerated in censuses. |
| institutions, Christian | Major Christian or church-operated or -related institutions of all kinds, i.e. fixed centers with premises, plant and permanent staff, excluding church buildings, worship centers, church headquarters or offices. For detailed statistics, see under: ecumenical centers, higher schools, medical centers, presses, radio stations, religious communities, research centers, seminaries, study centers, universities. |
| instrument | Any measuring device (Websters); in missiological usage, any of the 2,056 means or methods employed by churches and missions to record the progress and status of Christianity,and so recorded and described in the present WCE/WCT/WCD. |
Data on 18 categories of religion, including non-religious, by country, province, and people.
Data on all religions, Christian activities, and trends.
Membership data, year begun, and rates of change.
Population and religion data on all major cities & provinces.
Detailed information covering religion, culture, and geography.
A repository of historical data, including a chronology of Christianity from the 1st to 21st centuries.