In this Research Paper, ICCT Visiting Research Fellow Dr. Alex P. Schmid seeks to clarify some conceptual issues that tend to obscure the debate about how best to counter violent extremism. The main focus of this Research Paper is on obtaining a clearer understanding of what “Islamist extremism” entails in the context of the ongoing debate on allegedly “acceptable” non-violent extremists and “unacceptable” violent extremists. The author discusses a number of conceptualisations of religious extremism in the context of liberal democracies and also distinguishes, inter alia, between merely “not (yet) violent” militancy and principled non-violent political activism in the Gandhian tradition. The author argues that the distinction between “non-violent extremism” and “violent extremism” is not a valid one. The paper provides a set of twenty indicators of extremism that can be used as an instrument for monitoring extremist statements and actions, with an eye to challenging and countering such non-democratic manifestations.