As nouns the difference between ideology and extremist
is that ideology
is doctrine, philosophy, body of beliefs or principles belonging to an individual or group while extremist
Doctrine, philosophy, body of beliefs or principles belonging to an individual or group.
The study of the origin and nature of ideas.
Original meaning “study of ideas” (following the etymology), today primarily used to mean “doctrine”. For example “communist ideology” generally refers to “communist doctrine”; study of communist ideas instead being “communist philosophy”, or more clearly “philosophy of communism”; only rarely “ideology of communism”.
a person who holds extreme views, especially one who advocates such views; a radical or fanatic
holding extreme views, especially on a political subject
of, or relating to extremism