Can you ‘join an ideology’?

The word ideology is defined by Merrriam Webster as:

1 a : a manner or the content of thinking characteristic of an individual, group, or culture

b : the integrated assertions, theories and aims that constitute a sociopolitical program

c : a systematic body of concepts especially about human life or culture

2 : visionary theorizing

None of these definitions describes a group of people or a movement which makes the idea of 'joining and ideology' not 'wrong' but meaningless.

One can subscibe to or adopt an ideology or join an ideological group or a movement which promotes a given ideology but there is no sense in which one can join an ideology any more than one can join a set of religious beliefs or political theories. One can join a religion or a political party but not its defining concepts. The same thing applies to ideologies, they are abstract conceopts not groups of people.