Just a thought with questions...!
In Roman Catholicism the Mass was always said in Latin prior to Vatican council 2, then in the native language of what country the Mass was in there after.
I read that with Orthodoxy that the Divine Liturgy has always been said in the native language of what country it was in.
If this is the case, why does the Greek orthodox still use an ancient language that even the Greeks don't understand? why don't they change it to modern Greek? which is there native language.
Isn't this just the same as Catholicism using Latin, it is still a dead language.
This is one area where there is a lot of incorrect information out there. Perhaps the ideal
in Orthodoxy is for everyone to worship in his own native language. However, there are plenty of Orthodox who don not worship in the language of the common people.
Here are a few examples:
Russia: As far as I know, there are no parishes in the Moscow Patriarchate that serve the Divine Liturgy in modern Russian. Slavonic is used instead. However, even with the use of Slavonic, sermons are still in contemporary Russian. From what I have read, the Russian Church is now in the process of modernizing and updating the Slavonic language used in church to make it more understandable to the average Russian. Therefore, comprehension should improve, at least somewhat. Remember too, though, that Russian is used for other things besides the Divine Liturgy in Russia. Akathists and Molebens are generally prayed in Russian, not Slavonic, so quite a lot of understanding goes on there. Well educated Slavs can understand Church Slavonic, although I am told it is difficult. Most Slavic nations do have language courses in Slavonic at the university level. So it can be formally studied and learned, although I would think the numbers of people that actually learn it are rather small. I could be wrong.
Ukraine: Ukraine is divided into several different and often competing Orthodox jurisdictions. It is not united and under one jurisdiction like Russia. Because of that (and other issues) it is possible in Ukraine to attend a Divine Liturgy in modern Ukrainian. However, you will still find Slavonic Liturgies used in Ukraine as well, particularly in Moscow Patriarchate parishes in Ukraine. Although from what I have read, even the Moscow Patriarchate parishes there will sometimes have Ukrainian liturgies. I believe the Kiev Patriarchate promotes the use of modern Ukrainian for the liturgy, though. Ukraine is going to be a mixed bag. Expect some variation.
Romania: The Romanian Orthodox Church worships in Romanian from what I have been told. It is very easily understood by the Romanian faithful. Since the Romanians are Latins and speak a Romance language, you are not going to find much demand for Slavonic liturgies there. Apparently at one time the Romanian Church did worship in Slavonic, back in the 17th and 18th centuries. However, it switched to the Romanian vernacular ages ago and seems very content with it now.
Serbia and Bulgaria: Both countries traditionally worshiped in Slavonic. However, today having a Divine Liturgy in modern Serbian or Bulgarian is becoming more common. The Church Slavonic language of the liturgy is closer to modern Bulgarian than any other language. So apparently, Slavonic has the capacity to be more readily understood by the Bulgarians that it is by the Russians or the Serbs, whose contemporary language is quite different. Nevertheless, if you travel to Serbia or Bulgaria, be prepared for most liturgies to be served in Church Slavonic.
Greece: The Divine Liturgy in Greek is served in Koine Greek. This is ancient Greek that was developed during the Hellenistic period. It is the Greek of the Septuagint, the Ecumenical Councils and the Church Fathers. It is quite different from Modern Greek. Having said that, sermons in Greece are going to be in the vernacular, in what is called Demotic Greek. And those will be easily understood by the faithful. I am told that up until the mid 1980's, the public schools in Greece offered courses in Koine Greek. Under that older system of education, those Greeks who wanted to learn the language of the Church could do so. However, I am informed that the public school of Greece no longer offer courses in Koine Greek, so there is probably a greater lack of understanding now than there was in the past. There have been a couple of attempts to use modern Greek in the Liturgy, none of which have met with any success. So if you go to Greece, be prepared for Liturgies in Koine Greek.
Palestine, Jerusalem, Syria and Lebanon: In Antiochian parishes in the Middle East Arabic is going to be the language of the liturgy. The Antiochian parishes switched from Greek to Arabic back in the 1890s or even before in some places. However, because they used Greek for so long, you might have a little Greek thrown in here and there, such as a "Kyrie, eleison" or an "Agios O Theos." In Jerusalem itself, you can still encounter a lot of Greek at the Divine Liturgy, although Arabic is used there as well.
United States: The language will vary according to the ethnicity of the parish. OCA and Antiochian parishes are going to use lots of English. However, Slavonic is still used in the OCA in places. Some Arabic is still used by the Antiochians too. ROCOR is going to use Slavonic for its Divine Liturgies and Russian for its sermons, unless it is a specific English language parish, of which ROCOR has quite a few. The Greeks will almost always do SOME of the Liturgy in Greek, although most of them do portions of it in English too. Sermons will be in English generally, although I have seen parishes where the priest would give the sermon in English first, then preach it again in Greek. Serbian parishes will tend to use a mix of Serbian and Slavonic. Romanian parishes tend to use quite a bit of Romanian too, although they usually give the sermon in English.
I hope this helps.