One way to maintain strong cohesion within a group is to portray anyone outside the group as evil. Hoffer argued in The True Believer (1951) that radical movements are energized by hatred for their enemies.
What did Eric Hoffer say about belief in "devils" outside the group?
Mass movements can rise and spread without belief in a God, but never without belief in a devil. Usually the strength of a mass movement is proportionate to the vividness and tangibility of its devil.
Like an ideal deity, an ideal devil is omnipotent and omnipresent. When Hitler was asked whether he was not attributing rather too much importance to the Jews, he exclaimed: "No, no, no!...It is impossible to exaggerate the formidable quality of the Jew as an enemy." Every difficulty and failure within the movement is the work of the devil, and every success is a triumph over his evil plotting