Data source: Gina A. Zurlo and Todd M. Johnson, eds., World Christian Database (Leiden/Boston: Brill, 2024).
| Glossary item | Definition |
|---|---|
| Iranian | An Indo-Iranian ethnolinguistic family. |
| irregular attenders | Persons affiliated to churches but who attend services only irregularly, infrequently or occasionally. |
| irreligion | Hostility to religion: impiety, skepticism, disbelief, atheism, anti-religious humanism. |
| Irvingites | Catholic Apostolics originating in Britain in 1832, also called Old Apostolics; marked decline since 1900 due to dying out of clergy originally ordained after 1836 by Apostles. |
| Islam | (Arabic: submission to the will of God). The religious faith of Muslims (qv) who profess belief in Allah as the sole deity and in Muhammad as the prophet of Allah. |
| Islamics | The academic study of Islam. |
| islamization | The act or process of converting people, or of being converted, to Islam. |
| Ismailis | Followers of Ismailiya (also known as Seveners). Second largest sect of Shia Islam and itself divided into Nizari Ismailis (Khojas) and Mustali Ismailis (Bohras). |
| isolated radio believers | The total community of those persons (with their dependent adults and children, and other adherents) who derive their ongoing corporate Christian life primarily from isolated radio churches or isolated Bible correspondence course student groupings. |
| isolated radio believers | Persons in isolated areas with no churches or missions who have become Christians through radio programs. |
| isolated radio churches | New indigenous house churches, cells or nuclei composed of isolated radio believers (qv) brought into being solely through Christian broadcasting and/or Bible correspondence courses by mail, who due to geographical remoteness or other reasons are isolated from existing Christian believers and are ignorant of the existence of organized denominations, hence group themselves into these new fellowships. |
| Issei | (Japanese: first-generation). A Japanese immigrant to the Americas. |
| Italo-Albanians | Catholics following the Italo-Albanian rite. |
| Ithna-Asharis | Followers of Ithna-Ashariya (also known as Twelvers), largest sect of Shia Islam. |
| itinerant | Adjective describing an evangelist, missionary, or other church worker whose ministry involves being continually on the move from one city or people or country to the next. |
| Jacobites | Syrian Orthodox (qv), so termed after Jacob Baradaeus, bishop of Edessa (died 578 AD). |
| Jains | Followers of the two Jain traditions, Svetambara and Digambara; originating in India as a reform movement from Hinduism in the 5th or 6th century BCE. |
| Jansenists | Dissident Catholics in Holland who in 1702,1724 et alia formed separatist churches and were later termed Old Catholics (qv). |
| Japanese | An Asian ethnolinguistic family and people. |
| Japanese indigenous churches | Denominations indigenous to, and started by, Japanese. |
| Jehovah’s Christian witnesses | The preferred self-appellation of Jehovah’s Witnesses (qv). |
| Jehovah’s Witnesses | A marginal Protestant tradition begun in 1872 also called Russellites. |
| Jerusalem | One of the 4 original partriarchates of the Apostolic Church; now the see of 4 rival patriarchs: Greek Orthodox, Armenian Apostolic, Melkite and Latin. |
| Jerusalems | See holy cities. |
| Jesuits | Members of the Society of Jesus, Catholicism’s largest religious order; in 1975, 29,636 members (20,604 priests, the rest brothers), (1997) 22,580 in 1,931 houses. |
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.