From September 10th to September 28th 1918, Adolf Hitler was in Berlin on leave from the Western front. It is not clear whether he could read German newspapers on the battlefield (actually, in his regimental HQ) on a regular basis, but he definitely was able to do it in Berlin.
Germany and Russia were now allies, so it is not surprising that German media devoted a significant amount of their content to now Soviet republic. It is not surprising either that Gefreiter Adolf Hitler found the news from Russia utterly terrifying.
After seizing power in November of 1917, the Bolsheviks rapidly destroyed (or were well on their way to destroying) just about everything they could lay their hands on – the economy, the armed forces, the government system, the Christian Church (Orthodox, Catholic, Protestant, etc.), other religions, etc.
Almost right from the start, Lenin and his clique unleashed a ruthless and murderous terror not only on the elites, but on the “regular folks” (especially on peasants) as well. And started the bloody and destructive civil war. Within months, just about the whole country was plunged into chaos and essentially lay in ruins.
The key perpetrators of these monstrous crimes were Jewish. People’s Commissar for Foreign Affairs and later for the Armed Forces (and the second most powerful man in Soviet Russia) was Jewish.
People’s Commissar for Trade and Industry (largely responsible for the destruction of the Russian economy) Viktor Nogin was Jewish. Yakov Sverdlov – the head of the Soviet State – was Jewish.
Prominent members of Communist Politburo (de-facto Soviet government) Lev Kamenev and Grigory Zinoviev were Jewish. Yuri Larin – another destroyer of Russian economy – was Jewish. The list goes on and on and on.
And Vladimir Lenin who was in charge of this whole carnage, was one-quarter Jewish.
From all these horrifying news, Adolf Hitler could make only the obvious conclusions. That Bolshevism (a further development of Marxism) was, indeed, an existential threat to Germany, Europe and to the whole global human civilization (which was true and correct) and that it was a massive Jewish conspiracy (which was not).