This study proposed victimisation-by-ingroup consciousness as a novel concept, which denotes that intragroup violence or wrongdoings by some group members victimise other members of the same group and may elicit sense of physical, material, cultural and psychological sufferings among the victim members. Applying this concept to the context of religious radicalism, this study revealed that among a sample of Indonesian Muslims ( N = 810), the perceptions of physical, material and cultural sufferings positively predicted psychological suffering. This sense of psychological suffering turned out to motivate participants to perceive intragroup violence as illegitimate. This perceived illegitimacy of intragroup violence ultimately facilitated participants to report less emotional, attitudinal and intentional radical tendencies to support terrorists. Finally, we found as expected that Islamic blind patriotism negatively predicted, but constructive Islamic patriotism positively predicted participants’ victimisation-by-ingroup consciousness. These empirical findings broadly suggest that accepting the deficiency of the ingroup may be beneficial for tackling Muslims’ radical tendencies, but this prospect depends on modes of Muslims’ emotional attachment to their own group. We close by discussing the theoretical and practical implications of those empirical findings, as well as limitations and practical implications of this study.