Does anyone know why it is common practice to NOT translation certain words one often runs across in Orthodoxy (such as Orthodoxy!) into English, like Theotokos? It is my understanding that the usage with other Orthodox languages is to translate Theotokos from the Greek to "Mother of God" in whichever language....why not in English?
Great question! English has a long, long history of incorporating loan words into its use to serve particular needs. While those of us who grow up outside of the Church find some of the vocabulary strange, it is really no stranger than Christian vocabulary on the whole. Why Christ and not Anointed One? Why Baptism and not Plunging? Why Apostle and not Sent-one? Why Bible and not Book? All of these terms have come into English (via Greek and Latin usually) because they carried specific nuanced understandings.
I am not sure to which "Orthodox languages" you refer but in the case of Slavonic in its various forms it has indeed oftentimes, not always, but usually, translated hence Bogoriditsa
, a pure calque, for Theotokos. Yet much of the Greek liturgical vocabulary came into Slavonic intact. Romanian also has done similarly.
Orthodoxy is English, by the way. As is heterodoxy.