This paper raises the theme of radicalism in Islam (an analysis of movements and their effects on Islamic development). The approach or type of research used is descriptive qualitative with a literature study approach, then the existing data is collected, reviewed and analyzed based on literature analysis, then the results are presented descriptively. The results or findings of this research are that radicalism is an ideology that demands change and renewal in terms of the social and political order with mechanics in accordance with its idealism. In launching their movement, they tend to use violence by rejecting all ideas that conflict with their thoughts. Broadly speaking, the causes of the emergence of radicalism are religious, socio-political, and cultural emotions. These things arise from the dissatisfaction of a person or group of rules and regulations that apply. Furthermore, the impact is the notion of radicalism which is transformed into a radicalism movement which is identified with the term terrorism.

Keywords: Radicalism and Islam.