The article examines and analyzes the spread of Islamism or Political Islam movements in the Greater Mediterranean and their increasing influence on the socio-political situation in 2011-2021. The historical factors, which contributed to the emergence of the hearths of Islamic culture in the countries which entered the Arab Caliphate in the Greater Mediterranean parallel with the Antique centers of European civilization, are retrospectively exposed. The Islamist ideologues called the Ottoman Imperia the heir of the Arab Caliphate. The main doctrinal conceptions of Political Islam and its more influential movement “Muslim Brotherhood” (forbidden in Russia) are discovered. The factor of the Arab Spring, which considerably influenced the strengthening of the Islamist movements, as well as its continuation of the protests in the Arab countries in 2018-2021, is examined. The main attention is allotted to analyzing the actions of the Islamic movements in Tunisia, Egypt, Algeria, and in the Libyan and Syrian conflicts too. The influence of external actors, the most active of which was Turkey, is revealed. The author also analyzes the situation in the Arab-Muslim communities in the European Mediterranean on the example of France, where social-economic problems, aggravated by COVID-19, have contributed to the activation of radical Islamist elements. It is concluded that confronting the Islamist challenge is a complex and controversial task. Its solution depends on both forceful opposition to radical groups and an appropriate foreign policy. An important negative factor is the aggravation of socio-economic problems and crisis phenomena in the institutions of Western democracy, in response to which the ideologues of Islamism preach an alternative world order in the form of an “Islamic state”. At the moment the Western society and the countries which repeat its liberal model do not give a distinct response to this challenge.