This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Yi Seung-hun was a Korean scholar baptized in Beijing in 1784 by French Catholic missionaries serving the Qing court, becoming the first Korean known to have received Catholic baptism. No missionary had yet set foot in Korea itself; Yi Seung-hun encountered the faith only because he had traveled to Beijing as part of a Choson diplomatic mission and sought out the Catholic community there.
He returned to Choson Korea carrying religious books and a crucifix, baptized fellow believers, and by early 1785 a self-organized lay Catholic community was meeting in a house in Seoul, in what is now Hanseong. No Western priest reached Korea for years afterward, which makes the Korean Catholic Church unusual in Christian history: a church founded and led entirely by laypeople who had encountered the faith abroad and carried it home themselves, rather than one established by resident missionaries sent to found it.
That lay-founded beginning shaped how Catholicism first took root in Korea, spreading through a self-organized network of converts studying and baptizing one another before any ordained clergy arrived to formalize what Yi Seung-hun and his companions had already started in that house in Seoul.