Yiddish evolved over many hundreds of years much like the (Yin)English that is spoken in the Yeshiva and chasidik communities today.
Yidden across Europe spoke the local language of their countries, mainly German/Slavic/Russian languages and communicated with each other in writing and orally and much of this communication incorporated religious/torah themes since this was the life and existence of Yidden. So in a great sense, Yiddish is mamish a “holy” language and so to might (Yin)English be one day, l’chora.
Any language can be used for corrupt purposes. The evil personalities of our biblical history spoke lashon hakodesh since this was their everyday language. Was Korach or Eisav supposed to use a “foreign” language for their evilness?
You can’t read and understand the writings of Shalom Aleichem or other non-religious Yiddish writers without a good foundation in T’nach; Halacha and Minhagim; and even Talmud. While there is a certain purity in learning Torah in Yiddish, which can’t be replicated in any other spoken language today, R’ Yaakov Kamenetsky instructed that childern in Torah V’daas be taught in English because the Torah should not be made a “karban”, sacrificed, for the sake of Yiddish.
It was Lashon Hakodesh, the language of the Torah, not modern Ivrit, which unified Gedolim from all parts of the world.