There has never been a natural split, because at least the slavic languages are all daughters of Old Church Slavonic language or differently known as Old Bulgarian. There was not any vernacular slavic language prior to OCS, which obviously was a vehicular language.
You have a point that,
But when did it Heppened? at 6th cantury Ad or at 1700 AD? wich calendar we must use?
Anatoli Flamenko or Julian?
So church again strikes,
After Latin and Greek which are Clergy language, Now Slavic is clergy language,
the Truth is until a point yes,
I will make a comparison with Germanic,
Germanic were Spoken from Bastarnae to Saxons and from Visigoths up to Norge,
Germanic language is not 'made in Berlin' language, but a family of languages,
only in Deutschland how many dialects we have? and how many states?
that could give each state to have its own dialect-language,
But the reformation that started from Luther start giving a written speech, and when writen speech is done then starts a reformation and a more preservative language,
until Goete and Hanover literature, Deutsch would split more and more to dialects, but that was hold,
Same is with OCS, only stronger,
Cyril and Method gather syntax grammar and vocabulary mainly from Great Moravia, not Bulgaria, Bulgaria is the less Slavic language and population. and reconstruct, or just construct a language from a dialect that was the lighthouse of Slavic reformation and not only,
OCS is not an artificial language like Esperando, but a language spoken by some, that help reform All Slavic and para-Slavic languages to a comon quide-ruler,
I mean that later education uses Great Moravian dialect as primary ruler,
same in Germany they use Goethe as ruler, etc
understand that, A priest if speaks in another language nobody listen to him, so no work is done,
only when a priest the language of people, can have a result, that is religious book were translated,
besides one of the first religious tests in Albanian language is a liturgy, a Clergy text,
would that means that Albanian is a clergy language?
It is commonly held that Albanian must have been written at least since the 12th century as many facts would indicate.
[25] A 1332 document written in Latin by a monk, variously identified as either
Guillaume Adam (
Archbishop of
Antivari in the
Principality of Serbia from 1324 to 1341), or
Brocardus Monacus (Frère Brochard), testifies to the existence of written Albanian prior to the earliest records so far discovered.
[26]
he "
Formula e pagëzimit" (baptismal formula), which dates back to 1462 and was authored by
Pal Engjëlli (or Paulus Angelus) (ca. 1417–1470), Archbishop of
Durrës. Engjëlli was a close friend and counselor of
Skanderbeg.
[27] It was written in a pastoral letter for a synod at the Holy Trinity in Mat and read in Latin characters as follows,
Unte paghesont premenit Atit et birit et spertit senit ("I baptize you in the name of the Father and the Son and the Holy Ghost"). It was discovered and published in 1915 by
Nicolae Iorga.
[28]
Watch the above, if I follow your Logic then
Albanian is a Clergy language also, created by monks
and to use your vocabulary a Vehicular language.
So by following your way of Thinking,
in post about proto-Greek you say Greek naver existed but invented by church
Latin is also a clergy language,
now Slavic is a Church language,
by what we see Albanian is also a clergy language,
the only one left are the Germanic in Europe and Fino-Ugric languages,
are they connected with church also?
which language is not a clergy language?