Previously translated as The Tradition? (I’m not sure, the descriptions in the old glossary don’t have enough information to allow me to be sure, probably because I need some Chinese info to be sure).
This is the official “Religion” of the Zhou Empire, not in the western sense, but in the Chinese sense, closer to that of Taoism than anything else, even though the organisational structure is probably derived from Christian ones.
They have a pope, priests, churches and their doctrine is officially that of a single interpretation of “The Way” (think Taoism).
This is the reason why I consider them to be a religious “Orthodoxy”. There is no need to associate this with Christian Orthodoxy; think of this as Taoist Orthodoxy.