This article examines how doctrinal innovation led to the politicization of Falun Gong, a new religion in China. After it was outlawed in 1999, Hongzhi Li (李洪志), the charismatic leader of Falun Gong, developed a theory of resistance focusing on the strategy of "Clarifying the Truth." Guided and justified by the theory, FLG practitioners engaged themselves into various forms of collective activities against the Chinese government. The theory also helped Li to mobilize social resources overseas. Most importantly, the process of doctrinal innovation enabled Li to interact with his followers frequently and thus keep his charismatic authority in the group. In sum, the formulation of the "truth" theory not only led to FLG's politicization but also sustained the group's vitality by means of justifying the resistance, mobilizing social resources, and maintaining Li's charisma.