What is a Marxist? I believe that Karl Marx had two valid insights, and that he was mistaken about everything else. I see no value in the philosophy of Vladimir Lenin at all. Does that make me a Marxist.
As a cause and a philosophy socialism existed previous to Marxism. In the Communist Manifesto Marx criticized socialism.
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Preface to 1888 English Edition of the Communist Manifesto
Thus, in 1847, socialism was a middle-class movement, communism a working-class movement. Socialism was, on the Continent at least, ―respectable‖; communism was the very opposite...
In this way arose feudal Socialism: half lamentation, half lampoon; half an echo of the past...always ludicrous in its effect, through total incapacity to comprehend the march of modern history...
As the parson has ever gone hand in hand with the landlord, so has Clerical Socialism with Feudal Socialism...
Christian Socialism is but the holy water with which the priest consecrates the heart-burnings of the aristocrat...
Petty-Bourgeois Socialism...this form of Socialism...is both reactionary and Utopian...
German or “True” Socialism...While this ―True‖ Socialism thus served the government as a weapon for fighting the German bourgeoisie, it, at the same time, directly represented...a reactionary interest, the interest of German Philistines. I
Conservative or Bourgeois Socialism...It is summed up in the phrase: the bourgeois is a bourgeois – for the benefit of the working class...
Critical-Utopian Socialism and Communism...
The significance of Critical-Utopian Socialism and Communism bears an inverse relation to historical development. In proportion as the modern class struggle develops and takes definite shape, this fantastic standing apart from the contest, these fantastic attacks on it, lose all practical value and all theoretical justification.
https://www.marxists.org/admin/books/manifesto/Manifesto.pdf#:~:text=2 Genesis of the Communist Manifesto Marxists Internet Archive The
Those conflate socialism with Marxism know little about either.