An Introduction to the Orthodox Christian Church
One of the three branches of world Christianity and the major Christian Church in the Middle East and Eastern Europe, the Orthodox Christian Church, also sometimes called the Eastern Church, the Greek Orthodox, the Russian Orthodox or Orthodox Catholic Church, claims to have preserved the original and apostolic Christian faith. Figures for its worldwide membership range from 100 to 200 million, depending on the method of accounting.
Adapted from: John Meyendorff. The Orthodox Church. The Academic American Encyclopedia (Electronic Version), copyright © 1993 Grolier, Inc., Danbury, CT.