The word "Orthodox" comes from the Greek for "right teaching."
There are a multitude of churches that identify themselves as "Orthodox." No one of the Churches owns the name, so it can be invoked by any who wish to use it. As with Protestants, there is only one true statement that can be made about all of the Orthodox: they are not in communion with Rome. The manner in which they differ from Catholics in doctrine and discipline varies from one body to the next, because, in addition to desiring separation from Rome, they desire to be separate from one another. Each group must be dealt with in its own terms.
- It would be very difficult to find the right name for this Church. "Eastern" is too vague, the Nestorians and Monophysites are Eastern Churches; "Schismatic" has the same disadvantage. "Greek" is really the least expressive of all. The Greek Church is only one, and a very small one, of the sixteen Churches that make up this vast communion. The millions of Russians, Bulgars, Rumanians, Arabs, and so on who belong to it are Greek in no sense at all. According to their common custom one may add the word "Eastern" to the title and speak of the Orthodox Eastern Church (he orthodoxos anatolike ekklesia).
- The Orthodox, then, are the Christians in the East of Europe, in Egypt and Asia, who accept the Councils of Ephesus and Chalcedon (are therefore neither Nestorians nor Monophysites), but who, as the result of the schisms of Photius (ninth cent.) and Cerularius (eleventh cent.), are not in communion with the Catholic Church. There is no common authority obeyed by all, or rather it is only the authority of "Christ and the seven Ecumenical Synods" (from Nicæa I in 325, to Nicæa II in 787).