Whereas modern communication strategies have been celebrated for promoting ease of interaction, this chapter highlights that they have been deployed by some terrorist groups in Africa to threaten human security. It defines religious extremism in terms of the expression of extreme or violent actions or jihad on the basis of particular interpretations or understanding of religious teaching or scripture, especially the Quran. The chapter examines the (online) communication behaviours of extremists/terrorist groups in West Africa and Somalia that are often associated with Islam. It also examines religious extremism and its relation to violent conflict and describes the extremist violent activities of some identified African terrorist groups, and how contemporary media and the Internet have provided dynamic platforms for disseminating their message and ideology. Liebman views religious extremism as the desire to expand the scope, details and strictness of religious law, social isolation and the rejection of the surrounding culture.