On August 4, one of the 20th century’s most groundbreaking mission researchers passed away.

Dr David Barrett, 83, was founder-editor of the World Christian Encyclopedia and the World Christian Database.

This repository of statistical data includes information on 9,000 Christian denominations, 13,000 ethnolinguistic peoples, as well as data on 5,000 cities, 3,000 provinces and 239 countries. It has proved a vital compass for missions to steer by.

The headline story was that in the 20th century Christianity had become a truly global faith and was growing rapidly in the global south but declining in the north.

David Garrison of the Southern Baptist International Mission Board said, “More than any other man, David Barrett showed us what the whole world looked like through the lens of the Great Commission. He showed us how God viewed the world, and particularly the unfinished task."

British-born Barrett began his career as a mathematician researching aircraft flight design for the British Royal Air Force. He is credited as having worked on prototypes of supersonic aircraft which eventually led to the building of Concorde. Then he responded to a call to ministry within the Church of England.

In 1956 he went to Kenya as a missionary of the Church Missionary Society (CMS) where he remained for 20 years. Barrett studied as a Fulbright Scholar at Union Theological Seminary from 1961. Returning to Kenya, he set up a statistical unit for the Churches of East Africa and spent more than 10 years compiling and serving as editor of the World Christian Encyclopedia. This monumental work was first published in 1982 by Oxford University Press.

A second edition of the World Christian Encyclopedia was produced in 2001, with co-editors George Kurian and Todd Johnson and with it came a companion volume World Christian Trends (which he co-authored with Johnson). Barrett was also a long-time contributor of statistics on global religious adherence to the Britannica Book of the Year and the International Bulletin of Missionary Research. He moved on to work with the Southern Baptist Mission Board in 1985 and founded the Center for the Study of Global Christianity in 2006.

A very humble man, David never looked for public recognition but was tireless in promoting the cause of the "unreached". His statistical scenarios did not always please church leaders. Barrett edited a book of statistics intended to serve the 1968 Lambeth Conference of Anglican bishops. The then Archbishop of Canterbury was so displeased by Barrett’s projections of decline of Christianity in Western Europe that he refused to allow publication.

Well before Bill Gates emerged in the public eye , Barrett was convinced that computer networking would become highly important both in church administration and evangelistic outreach.

His farsighted perspectives were often shown to be true. In the mid-1980s he predicted that by the end of the 20th century the majority of Christian missionaries would come from the global South. He suggested this was probably already true, but the matter was not provable because so many of these missionaries had informal sources of support outside normal mission boards.