Christianity in Korea
Hangul, a phonemic Korean alphabet invented around 1446 by scholars in the court of Sejong the Great, was little used for several centuries because of the perceived cultural superiority of Classical Chinese (a position similar to that of Latin in Europe). However, the Catholic Church became the first Korean religious organization to officially adopt Hangul as its primary script. Bishop Siméon-François Berneux mandated that all Catholic children be taught to read it. Christian literature printed for use in Korea, including that used by the network of schools established by Christian missionaries, mostly used the Korean language and the easily learned Hangul script. This combination of factors resulted in a rise in the overall literacy rate, and enabled Christian teachings to spread beyond the elite, who mostly used Chinese. As early as the 1780s, portions of the Gospels were published in Hangul; doctrinal books such as the "Jugyo Yoji" (주교요지) appeared in the 1790s and a Catholic hymnal was printed around 1800.
Gari Ledyard
The "Hunmin Jeong-eum" credits the 古篆字 ""Gu" Seal Script" as being the source King Sejong or his ministers used to create hangul. This has traditionally been interpreted as the "Old" Seal Script, and has confused philologists because hangul bears no functional similarity to the Chinese seal scripts. However, 古 "gǔ" had more than one meaning: besides meaning "old", it could be used to refer to the Mongols (蒙古 "Měng-gǔ"). Records from Sejong's day played with this ambiguity, joking that "no one is more "gu" than the "Meng-gu"". That is, "Gu Seal Script" may have been a veiled reference to the Mongol Seal Script, or Phagspa alphabet. ("Seal script" is a style of writing, used for name seals and official stamps. Phagspa had a seal script variant modeled after the appearance of the Chinese seal script of its day. In this guise it was called the 蒙古篆字 Mongol Seal Script, with only the initial character distinguishing it from the 古篆字 credited by the "Hunmin Jeong-eum" as the source of hangul.) There were many Phagspa manuscripts in the Korean palace library, and several of Sejong's ministers knew the script well.