Is there an elementary structure of religous vigilantism ? If so, what might be the key elements ? This paper is an attempt to think through these questions using examples of vigilantism  in Indonesia targeting  the Ahmadiyah minority, a controversial Sunni Muslim reform movement. The paper argues that religious vigilantes engage in immunization operations that aim to safeguard the 'Muslim community' by affirming its core values and ideological boundaries. Particular attention is given to  the territorial dimensions of anti-Ahmadiyah violence over the past two decades.