A systematic review: unveiling the complexity of definitions in extremism and religious extremism

This study presents a systematic literature review (SLR) on the evolving and often ambiguous concepts of extremism and religious extremism, addressing the ongoing definitional challenges that hinder both academic discourse and policy development. Recognizing the growing significance of these phenomena in contemporary global contexts, the review adopts the PRISMA 2020 framework alongside the SPIDER tool to guide the formulation of research questions and article selection. A comprehensive search of the Web of Science and Scopus databases yielded 510 records, from which 11 articles published between 2018 and December 2023 were deemed eligible for final analysis. The selected studies were subjected to qualitative synthesis through thematic analysis, allowing for the identification of recurring themes and interpretive patterns. Three major themes emerged—belief, behaviour and absence of a universal definition—complemented by four sub-themes: uncompromised, biased interpretation, specific society and violation of true teaching. These findings underscore the complexity and multidimensionality of extremism, revealing how rigid ideological convictions and intolerance for dissent often drive behaviours that deviate from societal norms and ethical standards. Moreover, the review highlights the unique characteristics of religious extremism, which involves the manipulation of doctrinal teachings to justify exclusion, violence or intolerance. The lack of a consensus on the definition of extremism complicates identification and intervention efforts, particularly within legislative frameworks and societal applications. As such, this study emphasizes the urgent need for coherent, context-sensitive definitions that can inform more effective policy measures. It calls for interdisciplinary collaboration among scholars, policymakers and community leaders to refine the conceptual boundaries of extremism and religious extremism. In addition, long-term strategies should prioritize educational initiatives, social reforms and the promotion of democratic values to address the root causes of extremism and cultivate more inclusive, resilient societies.