This research is an attempt to examine some of Ibn Taymiyyah’s writings and their influence on the latest radical and extremist movement. Writings by Ibn Taymiyyah had a significant impact on the salafiyah movement, which carries the spirit of tajdīd and iṣlāḥ (renewal). Some of his views are often cited by the latest extremist and radical groups to justify their approach, which tends to be harsh towards fellow Muslims. This study specifically intends to examine Ibn Taymiyyah’s concept of tawḥīd as it relate to his influence on the radical tendencies of some salafiyah groups. The study utilize textual method and conceptual analysis on the works of Ibn Taymiyyah and also the writings of the salafi scholars. The study reveals a definite influence of Ibn Taymiyyah’s ideas on radical groups, particularly in their view of tawḥīd and their categorization of it into three categories. The classification of tawḥīd could be the basis for the tendency of takfiri group to rise amongst Muslims. But reading Ibn Taymiyyah’s texts attentively, thoroughly, and without taking anything literally could prevent one from developing radical or extremist tendencies