This article deals with the anti-ecumenical movement in Russian Orthodoxy, representing aspects of religious separation and isolationism. The authors analyze sociocultural and political premises, upon which this Orthodox isolationist ideology is based, including such elements as defensiveness, obsessive securitization, intertwined with revanchism, geopolitical resentment, and idealization of the Soviet past. The authors emphasize the “mobilization consciousness” — a psychological conviction that any positive transformation process in Russia might happen only in circumstances of extreme stress and the feeling of threat. The article further presents a comparison of Orthodox fundamentalists and radical right movements.