From Wiki:

Rastafari say that they reject “-isms”. They see a wide range of “-isms and schisms” in modern society, for example communism and capitalism, and want no part in them. They especially reject the word “Rastafarianism”, because they see themselves as “having transcended -isms and schisms.” This has created conflict between some Rastas and some members of the academic community studying Rastafari, who insist on calling this faith “Rastafarianism” in spite of disapproval this generates within the Rastafari movement. Nevertheless, the practice continues among scholars. However, the study of Rastafari using its own terms has occurred.