This article focuses on the enigma of Catholic Marian revolutionary movements during the decade-long conflict on the island of Bougainville, Papua New Guinea at the end of the twentieth century. These religious movements embody the legacy of a colonial history as well as people’s responses to poorly monitored resource extraction, social and economic displacement, regional factionalism, and years of fighting by Bougainvilleans against the Papua New Guinea Defence Force. At the same time, the movements’ popularity throve on leaders’ reputations for their religious knowledge and their mobilization of people based on religious faith. During the conflict Bougainville came to be seen by many residents as holy land (Me’ekamui). According to Francis Ona’s Marian Mercy Mission and Peter Kira’s Our Lady of Mercy movements, the covenant land of Bougainville had to be safeguarded from Satan, represented by Papua New Guinea and an Australian copper mining company, in the freedom struggle conceived as a Marian holy war.