Well-known songs of colonial Korea such as “Kagop’a” and “Pongsŏnhwa” appear to be secular songs, but their origins lie in the complex intersection of North American Christian missions, Korean cultural life, and Japanese colonial rule. This article explores the historical significance of secular sentimental songs in colonial Korea (1910–45), which originated in mission schools and churches. At these sites North American missionaries and Christian Koreans converged around songwriting, song publishing, and vocal performance. Missionary music editors such as Annie Baird, Louise Becker, and their Korean associates relied on secular sentimental songs to cultivate a new kind of psychological interior associated with a modern subjectivity. An examination of representative vernacular song collections alongside accounts of social connections formed through musical activities gives a glimpse into an intimate space of a new religion in which social relations and subjective interiors were both mediated and represented by songs. The author argues that this space was partly formed by Christianity’s fugitive status in the 1910s under the uncertainty of an emergent colonial rule and traces the genealogy of Korean vernacular modernity to the activities of singing in this space, which she calls a fugitive Christian public.