The presence or absence of violence has been a long guiding benchmark to determine degrees of Islamist extremism. Yet fixations on violence has reduced the discourse into two divergent camps: those who view non-violent Islamists as enablers of terrorism, and those who view them as firewalls. Contributions to the debate over the role non-violent ideas play in violent radicalisation have varied according to whether emphasis is best placed on groups or individuals, and whether it is patterns of behaviour, or differences in ideology, that should inform categorisation into violent or non-violent extremism. Through a synthesis of relevant literature to date, this paper critically assesses the validity of the binaries of violent and non-violent Islamism. The paper calls for a distinction between strategic non-violence, which is pragmatic and open to adaptation, and principled non-violence, which is consistent and committed. While evidence of groups shifting towards a strategic non-violent posture accumulates, there are few cases in the literature where principled non-violence accurately applies.