There are some religions (either fictitious or not) that use a liturgic language for their rites and ceremonies. That language must be learned by all of their adepts, and sometimes it is even forbidden to translate the {{holy book}}s to another language, mainly because it is said to have been created by God (or the gods), or to preserve its sacred euphony [[BuffySpeak (good-sounding-ness)]].

TruthInTelevision, as it can be noticed below. See also LanguageOfMagic and BlackSpeech.
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!!Examples:

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[[folder:Literature]]
* In ''Literature/{{Elantris}}'', the Derethi religion has Fjordell, language of the Empire where the Derethi church is centered, as its official language. At one point, Derethi high priest and AntiVillain Hrathen debates with himself whether or not it's right to preach the religion to new converts in their native tongue, since Jaddeth (the Derethi god) revealed himself in Fjordell[[note]]May not sound like a big deal to us, but to the extremely dogmatic Derethi, it's a pretty significant hurdle[[/note]]. Being the MagnificentBastard that he is, Hrathen comes up with an elegant solution: Preach to people in their native language, ''then'' teach them Fjordell once they're converted.
** This trope is parodied in another of Creator/BrandonSanderson's works, ''Literature/TheAlloyOfLaw'', with the "High Speech" which the readers will recognize as the rather ridiculous sounding [[JiveTurkey thieves' cant]] from the ''{{Mistborn}}'' trilogy.
* In Creator/AnneMcCaffrey's ''Acorna'' series, one planet considers Acorna a god because she speaks the native tongue of ''her'' people. They had been visited many ''many'' years ago by [[spoiler:Aari and Grimalken]], and their priests had miraculously picked up the language in a single visit.
* [[DichterUndDenker German philosopher]] Oswald Spengler speculated in his non-fiction book ''Literature/TheDeclineOfTheWest'' that in the Stone Age, language (as in, speaking) may have been restricted to the priests, just as was the case with writing in some cultures.
* ''Literature/TheLordOfTheRings'': Quenya appears to have been this for the Númenoreans, and possibly for others as well.
** Or it was "What rich people spoke"(kinda like French in the eighteenth century). Maybe a bit of both.
* In the Literature/FirebirdTrilogy, the Sentinels use Ehretan, the language of the world they originally came from, for their religious ceremonies, and one of their holy books is forbidden from being translated out of Ehretan.
* Language is a major source of spiritual power in Epstein's Literature/CaptiveOfTheOrcs. Dallet develops spiritual powers as he analyzes the holy name, one letter at a time.
* In ''Literature/TheYiddishPolicemensUnion'', Landsman believes that Yiddish is for speaking to people, and that Hebrew is for talking to God.
* The language of the deeply religious Ulgo people in ''Literature/TheBelgariad''. It's the only exception to the CommonTongue spoken by everyone else on the planet.

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[[folder:Tabletop Games]]
* ''TabletopGame/{{Warhammer 40000}}'' has Binary for tech priests.
** It's not ''holy'' per se, but High Gothic is a more formal tongue used by the elite and the Administratum.
* In the TabletopGame/WarhammerFantasy Roleplaying game, the priests of Sigmar learn the Dwarven language.
* ''TabletopGame/DungeonsAndDragons'' has the language called Celestial for the native tongue of the heavenly planes. For evil cultists, there is Abyssal and Infernal, the languages of demons and devils, respectively.\\
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Druidic is also an example: all druids know Druidic, and if a druid teaches Druidic to a non-druid, they lose all their druid powers.
* ''TabletopGame/{{Exalted}}'' has a {{Zigzagged}} example. The Old Realm is the language of the creators of the world ([[OurTitansAreDifferent called primordials]]), but in the distant past, the gods [[TurnedAgainstTheirMasters rebelled]] against said creators. The creators were defeated, and imprisoned in AnotherDimension called {{Hell}}. Therefore, the Old Realm turned from SacredLanguage into BlackSpeech in the perception of most of the world. It ''remains'' Sacred for the cultists who worship the defeated creators.
* In ''TabletopGame/{{Ironclaw}}'' Magniloquentia, the ClassicalTongue of the city of Triskellion, is the Church of S'allumer's holy language, and required to cast Sacerdotal magic (but not the WhiteMagic most priests cast). Though most of their scripture is written in modern Calabrese and few priests know how to speak or read the old tongue.
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[[folder:Video Games]]
* ''VideoGame/{{Blood}}'' has the cultists speaking in "Domus Durbendia", a fake language similar to Sanskrit/Latin.
* In the VideoGame/DeptHeaven series, Asgard has a special classical language that's referred to as the Sacred Tongue. While all characters from Asgard conveniently speak Japanese(/English) for the sake of the players and other characters, someone's fluency in the Sacred Tongue (which is rendered in Greek letters) is incontrovertible evidence that they are from Asgard. This is an early plot point in ''RivieraThePromisedLand'', where Ursula's knowledge of the Sacred Tongue doesn't quite match up with the image Hector wants the main characters to have of her.
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[[folder:Real Life]]
* Hebrew for Jews -- though the language has been updated for common speech in Israel, and a number of important Jewish texts are written in contemporary languages.\\
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The Jews are by far the most serious about maintaining the sanctity of their religious language. A small but significant minority of Ultra-Orthodox Jews--particularly Hasids--regard the use of Hebrew for day-to-day conversation as ''blasphemous''; even the ones who live in Israel refuse to learn Modern Hebrew and continue to communicate exclusively in Yiddish.
* Arabic for Muslims. The translation of the Qur'an into other languages is permitted in Islam, but these translations are considered paraphrases or study aids, and not spiritually valid. This is related to its roots as an oral tradition and Arabic's nature as a phonetic language. In fact, the written form of Arabic was originally formalized in part due to the need to record the sacred verses of the Qur'an permanently and all together.
** Various sects differ on whether required prayers can or should be spoken in local vernacular or only in Arabic.
** A common misperception of (non-Arab) Muslims and non-Muslims alike is that the Arabic language is sacred. It is not-- only the Qur'an is sacred. Just because you say something in Arabic won't make a (learned) Muslim agree more with you (i.e., no Arabic AltumVidetur).
* For over a thousand years (~500-1517 AD) Latin was the Sacred Language for western Christians, and remained so for Catholics up until the 1960s, and until 2014 it was still the language in which all official Papal edicts and other high-level Vatican documents were written. It is still used in some ceremonies and masses.
* Greek for Greek Orthodox Christians. Note that Liturgical Greek is rather archaic and not entirely the same thing as Modern Greek--although it's closer to Modern Greek than it is to Classical Greek.
* Old Church Slavonic for the Russian [[OrthodoxChristianity Orthodox Church]].
* Similarly, the Coptic language (the late form of the [[AncientEgypt ancient Egyptian]] language) in the Coptic Orthodox (Egyptian Christian) Church.
* The same applies for the Ge'ez language (the tongue of the ancient and medieval Ethiopian empires) in the Ethiopian and Eritrean Orthodox Churches.
* Most varieties of Protestant Christianity avert this, holding that the right language for the Gospel to be spoken in is whatever the listener will understand. Thus, as living languages change, the Bible regularly needs to be re-translated from the original Hebrew (in the Old Testament) and Greek (in the New Testament). However, "most" here by no means means "all" ...
** Elizabethan English almost manages that in some Protestant circles simply because when well done, King James English sounds [[RuleOfCool cool]]. After all, would you rather your Bible said, "For unto us a child is born", or "We're gonna have a kid"? A small subset of fundamentalist Protestants, the King James Only movement, holds that the King James Bible is the best Bible; depending on which flavor of King-James-Onlyism you follow, the KJV derives its authority either from the truest Hebrew and Greek sources or from God's re-revelation of the Bible to the KJV translators. Unsurprisingly, King-James-Onlyism is associated with Anglophone countries.
** Interestingly, some Anabaptist congregations--particularly Old Order Amish--in America still use Alemannic High German in church even though they speak English in their daily lives.
** DoubleSubverted by the Finnish Lutheran Church. While the official liturgic language is Finnish, the priests and clergy are required to know also Hebrew, Greek and Latin in order to be able to understand and interpret the original scriptures in the original languages.
* Hinduism: The old Hindu vedas (scriptures) are written in Sanskrit. Pāṇini wrote on Sanskrit morphology and syntax for the sake of preserving the language as it was intended by the gods. He lived during the 4th century BC and is considered to be the first linguist. Since Sanskrit is one of the oldest known Indo-European languages and therefore very similar to ancestral forms of Latin, Greek, Russian, Persian, and even English, this work is one of the most important in the history of linguistics, up there with the Rosetta Stone. Ironically, Paninian Sanskrit was actually a modest simplification of the older forms used in the Rig-Veda, making Sanskrit in a sense one of the earliest recorded {{ConLang}}s.
** Modern Hindi is this to Indo-Caribbean people in UsefulNotes/{{Guyana}} and UsefulNotes/TrinidadAndTobago. To clarify, the Indo-Caribbean people are descendants of indentured servants brought over by the British from India to the Caribbean. Over the years, Hindi stopped being the primary language, and everyone now speaks English (albeit a Caribbean dialect of it) as the primary language. Hindi only survives in religious texts and among the priesthood and temple singing groups, and your average Hindu in the Caribbean thinks of Hindi as a liturgical language, not something that one would speak in everyday life. People in India, of course, still speak Hindi as their most common language, and the linguistic differences between the Indians and the English-speaking Indo-Caribbeans often results in massive InternetBackdraft today when Indians accuse Indo-Caribbeans of "acting white" by speaking English as their primary language. The Indo-Caribbean people, for their part, retort that even though their ancestors were Indian, they now consider themselves to be a different--albeit related--culture.
* The original Buddhist scriptures (sutras) were written in Pali/Maghadi, which is referred to in linguistics as a Prakrit ("common speech", compared to Sanskrit, which literally meant "refined speech" and approximates rather closely to the fictional use of [[ClassicalTongue "high speech"]]). Pali in turn may be ancestral to Sinhala, the most common native tongue in Sri Lanka. [[note]]Nobody seems to know for sure the name used by native speakers for Sanskrit and its relatives and descendants, although at one point it may have simply been known as ''vak'', which literally just means "speech" and is probably cognate with "voice" and "vocal". This is surprisingly common in modern languages; for example, in Spain, the Asturian and Aragonese languages, both close relatives of Spanish and Portuguese, are called respectively ''bable'' and ''fabla'', which both more or less mean "how we talk around here".[[/note]]
* Similarly, although Zoroastrian is very much a minority faith in its traditional Iranian homelands, Zoroastrians still preserve Avestan, a language closely related to but distinctly separate from Old Persian (and, slightly further afield, Sanskrit) in a liturgical function, although most speak other languages (particularly the Parsis, an Iranian ethnic minority and Zoroastrian remnant most closely associated with India, and speaking local languages or English rather than their ancestral Iranian languages).
* Sumerian for the Akkadians and Babylonians. Historians record that the Akkadians, always fond of oddball religious practices, had at least one ritual involving two people whispering the same prayer into a bull's ears--Sumerian in one ear, Akkadian in the other.
* Etruscan survived for some time as a ritual language after the language had "died". There was even a (now lost) Etruscan-Latin dictionary. (Which is kind of a shame, given that we only partially understand Etruscan now.)
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