British mission strategist Patrick Johnstone first wrote Operation World in 1974. Further editions were published every several years, and by the end of the 20th century it had become one of the best-selling and most influential mission books in history. Operation World profiles each country in the world, providing reliable analysis of various demographics including the state of Christianity, and highlighting the present spiritual climate and prayer needs of each region.

Johnstone teamed up with Jason Mandryk to produce the 2001 edition of the book. Utilizing numerous sources and researchers, Johnstone and Mandryk listed a total of 91.575 million Christian adherents in China. This figure was comprised of 23 million TSPM believers, 11.7 million Catholics, and the rest comprised of various Protestant groups, including house church networks.

Although I believe some of the statistics provided in the provincial summaries to be askew, overall I believe their research of the size of the Chinese church is among the most accurate and reliable to emerge in recent decades. In their own words, they “sought to painstakingly piece together the biggest picture from every scrap of evidence available.” The authors’ desire to listen and learn from numerous sources has given their survey a ring of authenticity.