Buddhism and Musok in Korea have been closely interrelated in many ways for a long time. Their affinities and similarities are acknowledged in terms of inclusiveness, inter-relationships and syncretism, while their differences are underlined by exclusiveness and specificities. In the classification of religions Musok is considered a popular religion, not an institutionalized religion like Buddhism. There has been little scholarly interest in the religious phenomenon that stands between Musok and Buddhism. This space is occupied by the hybrid religious figure of the posal. The posal is a religious officiant sharing her name with Buddhist officiants and also displaying similarities in her religious practices with the mudang. The posal’s religious identity, as I argue in this paper, threatens Musok and Buddhism. From the posal’s perspective, Musok and Buddhism are both institutional and thus have clearly outlined beliefs. Indeed, from this perspective, Musok is not less institutionalized than Buddhism. The analysis of the relationship between the posal and Musok and between the posal and Buddhism is based on data collected from mudang and Buddhist blogs and other websites. The discourse analysis will demonstrate the ambiguous boundaries of identities between the religious figures of the mudang, posal and Buddhists and how the posal’s lack of institutional identity and status cause the mudang and Buddhist to use their institutional authorities to curse the posal in two respects: spiritually and socially.