For what it's worth, unlike Christianity, Islam, Freemasonry, etc. there is no such thing as 'cultural marxism'. The modern usage seems to be as a catch-all term used by (literal) fascists and fascist-associated groups for literally any progressive or postmodern viewpoint, but in addition usually has the connotations of 'cultural perversion' and 'conspiracy'. Prior usage seems to be to describe an anti-semitic conspiracy theory (that is in part related to modern usage), and the term as a whole dates back to when it was coined by the German Nazi Party ("Cultural Bolshevism" - Kulturbolschewismus) to describe modernist art movements that they thought were 'degenerative'.
Rational Wiki's second description is incredibly descriptive:
""""Cultural Marxism" (both uppercase) is a common snarl word used to paint anyone with progressive tendencies as a secret Communist. The term alludes to a conspiracy theory in which sinister left-wingers have infiltrated media, academia, and science and are engaged in a decades-long plot to undermine Western culture. Some variants of the conspiracy allege that basically all of modern social liberalism is, in fact, a Communist front group."""
See:
https://rationalwiki.org/wiki/Cultural_Marxism
https://en.wikipedia.org/wiki/Frankfurt_School#Cultural_Marx...
My point wasn't that Marxism as a whole does not exist, as you seem to have replied. My point was that "Cultural Marxism" specifically does not exist, and is literally neo-nazi propaganda.
Biological theories - in such theories biology is key factor. For example: scientific racism (Arthur de Gobineau), Social Darwinism (Herbert Spencer), or theories where you treat civilisations like a living organism that always have to go through 3 phases: youth/development, adulthood/prosperity, senility/decline (for example Oswald Spengler theory).
Economical theories - economy as key factor. For example: Liberalism, Marxism, etc. Right now those theories are very popular, a lot of people assume that there is actually one big human civilisation and differences are just in economic level of each country/region/group.
Ideological theories - ideology/religion as key factor. Examples: Christianity, Islam, Freemasonry, Cultural Marxism, etc.
There were also attempts to merge all of those aspects: Toynbee, Koneczny (someone mention his work in one of the comments), Huntington (personally I think he ineptly copied Koneczny work).
Because of Pax Americana after WWII most people start belive that liberal democracy and capitalism was finall destination of all civilisations (Fukuyama famous book: "End of history"). But right now with rise of China and their model of state/economy/politics people start looking for much broader theories.