Really, though, Leninism was a kind of offshoot rather than theoretically central. Could you imagine what Marx’s response would have been to Russia as the vanguard of socialist revolution?!
O.K. Kaninchen… I will take your bait even though I assume this is slightly off the OP. I think Marx, had he been alive and though this of course is counterfactual guessing (though fun), would have gladly joined and tried to run the Russian Revolution and concomitantly hit on Krupskaya, ahem…given his biography.
I believe that for Marx, his hatred of capitalism combined with his personality (in Bakunin’s words: “Marx is lacking in nobility of soul…a most dangerous personal ambition has eaten away all that is good in him…the acquisition of personal power is the aim of all his endeavours. Marx does not believe in God but he believes much in himself and makes everyone else serve himself. His heart is not full of love but of bitterness and he has little sympathy for the human race,” - would lead me personally to assume he would have jumped at the chance for political power Lenin took in October 1917 with a de facto coup in Russia launching the Workers’ State. Marx was hungry for power.
I recall that Lenin, though influenced by the SRs and an ethnic Russian, always assumed Germany, given Marxist theory as the most advanced capitalist state, would be the first to put in force the Dictatorship of the Proletarian. This view was held by Marx too. Lenin, Trotsky et al. cared not for which country began the Class Revolution just that given the Marxist dialectic, it would be the most advanced economies. Lenin believed this just as much as Marx and hence his surprise at Russia being the first revolutionary state and the firm early belief of the early Politburo that Poland, Germany, and perhaps England would surely fall quickly from the Russian beachhead. They believed in this in all seriousness from 1917- 1924. They had battle maps put up during the Comintern (I believe) Congress in Petrograd in 1920 when the Reds advanced on Poland (and hopefully to Germany) and how the Revolution would have spread showing the Red Army’s advances.
Surely Marx would have made the same calculation Lenin made on the spot, grab Russia as a beachhead and the rest would follow.
Marx never rejected violence or terrorism when it suited his tactics. Addressing the Prussian government in 1849, he threatened: "We are ruthless and ask no quarter from you. When our turn comes
we shall not disguise our terrorism." (emphasis, mine) In the Plan of Action for the following year distributed in Germany Marx specifically encouraged mob violence.
The ironic thing with Marx is that while he wrote so much of workers’ exploitation in the abstract, he had no problem exploiting his own family ruthlessly. Much easier to argue to fight exploitation in the abstract for all of Mankind then actually dealing with it in your own personal life. In Paul Johnson’s opinion, Marx revealed an intellectual snobbery like Lenin, and Marx, “never set foot in a mill, factory, mine or other industrial workplace in the whole of his life.” To Johnson, (though this may be somewhat a stretch), “there is nothing in the Stalinist epoch which is not distantly prefigured in Marx’s behaviour”. (i.e. Marx’s habit of saying ‘I will annihilate you’ in all seriousness).
Sometimes Marx’s poetry is overlooked in looking at his motivations. Poems with names like “Savage Songs” encompass hatred, a fascination with violence, even suicide pacts. Marx was fond of quoting Mephistopheles’ line from
Faust: “Everything that exists deserves to perish.”
In December 1882, Marx exulted at his growing influence in Russia: “Nowhere is my success more delightful,” and he boasted that “it gives me the satisfaction that I damage a power which, next to England, is the true bulwark of the old society.”
And I note you mention technological advancements militating against historical determinism. I believe this also happened in the modern days to another philosopher influenced by Hegel, like Marx, Francis Fukuyama and his argument of The End of History. 10 years within publishing his thesis, he was already backtracking on his initial prognostications, claiming he could not have foreseen developments in technology. hmm
For many reasons, if the Church wants to look for certain support for critiquing certain elements of capitalism, it is hard to know why some would cite Marx?