This paper is the first of a series of papers which aims to address Islamist violent radicalization from different angles: the nature of violent radicalization in the context of Spain, a comparison between European, North American and Indian violent radicalization, the need to refine territorial radicalization indexes within the context of preventing violent radicalization and the relation between Islamist violent radicalization and other forms of violent radicalization in Europe. This set of articles builds upon the general theoretical framework set by the author on two previous works (García, 2018; 2019). These works are framed under the known conception of three layers of micro, meso and macro factors contributing to violent radicalization processes (McCauley, Moskalenko, 2017). The paper starts by defining Islamist violent radicalization, then it explores different theoretical explanations and finally proposes an explanatory hypothesis that is tested against, on the one hand, data proceeding from different institutional sources in Spain and, on the other, some initial conversations which will become life stories and a in depth interviews to Spanish security officials and people who whether radicalized and regretted or lived very close to others that did it.