This study argues that since the end of World War II, the Taiwanese Presbyterian Church’s practical institutionalised arrangements for evangelisation have had the unintended consequence of creating an imagined multi-layered aboriginal national Subject. The argument is founded upon analysis of three main points. First, aboriginal members’ daily practices within the three-level federalist church polity formed in their minds an acquired “schema”, a ready-made cognitive structure that could be easily appropriated by them to imagine their own nations in a certain way. Second, when the Church promoted the translation of the Bible and hymns into aboriginal vernaculars for practical evangelising reasons, it unintentionally created tribe-based cultural-linguistic mediums as national languages upon which the contents of aboriginal nations could be elaborated and reproduced. This step further consolidated tribe-based ethnic categorisation and facilitated the reification of aboriginal nations. Third, since aboriginal ministers and elders were institutionally endowed with many strengths in comparison to other aboriginal elites, they came to serve as human activators in formulating and spreading the imagination of the multi-layered aboriginal national Subject.