For Catholic missionaries in the early twentieth century, the only way to achieve true conversion of Timorese ancestral ritualists was the deliberate destruction of sacred lulik houses. Although Timorese allegedly participated enthusiastically in this destruction, lulik (a term commonly translated as sacred, proscribed, holy, or taboo) remains a key part of ritual practice today. This article offers a dynamic historical analysis of what may be described as a particular form of Southeast Asian animism, examining how people's relationships with sacred powers have changed in interaction with Catholic missionaries. It links the inherent ambivalence of endogenous occult powers to religious and historical transformations, teasing out the unintended consequences of the missionaries' attempts to eradicate and demonize lulik. Comparing historical and ethnographic data from the center of East Timor, it argues that, contrary to the missionaries' intentions, the cycles of destruction, withdrawal, and return that characterized mission history ended up strengthening lulik. Inspired by anthropological studies of “taboo” and “otherness,” especially the work of Mary Douglas and Valerio Valeri, this article makes visible the transformation of the sacred in relation to outside agents: when relations with foreign powers were productive, the positive sides of lulik as a source of wealth and authority were brought out; yet when outsiders posed a threat, the dangerous and threatening aspects of lulik were accentuated. This analysis allows us to highlight the relational dimensions of sacred powers and their relation to ongoing social transformations.