Maybe my theological awareness may not always be all that it should so perhaps I am misunderstanding your posting. To me it appears to distinguish Orthodox Christianity from the Catholic Church and to distinguish Orthodox Christianity from "the true Church and the protector of the faith." Maybe it's that 'but' that's confusing me. There is Orthodox Christianity but "the Catholic Church is the true Church and the protector of the faith."
To me this implies or suggests that whatever Orthodox Christianity is, it is somehow to be distinguished from the Catholic Church - or perhaps you mean the Roman Catholic Church? In which case I suppose you mean that it is the Roman Catholic Church, as distinct from Orthodox Christianity, which is the true Church?
Do you think you could possibly manage to put this clearer for me please?