I entered, "The Orthodoxy in Russia" and it was marked wrong. This seems important to include since it conveys the same meaning and seems to also be a more literal translation.
Me too, I also find it hard to understand when THE is supposed to be used and when it's just there but not said. Here it is not used, why? And/ or how do I know it is not?
Orthodox church = Ορθόδοξη εκκλησία, meaning the organisation, or a specific church, depending on word capitalisation.
Orthodoxy = the whole community of orthodox Christians.