I'd say its 1917 tbh. I'm going to get a lot of flak for this, but imo, Russia had historically been the defender of Christianity and European civilization for the last millennia.

They destroyed the Jewish Khazar Empire. They absorbed most of the blow from the Mongol invasion. Destroyed the turkic khanates that raided and terrorized Europe for centuries. They invaded and destroyed the Crimean Khanate that enslaved millions of Europeans for centuries.

And in the 19th century, they almost single handedly liberated most of the Balkans from Turkish occupation. Above all, for centuries they contained the world's largest Jewish population, and greatly reduced their ability to corrupt the world by shuttering them in the ghettoes.

The Bolshevik revolution however, turned Europe's greatest champion into its worst enemies. From there, marxism was exported and financed worldwide.

If the Bolshevik revolution never happened, there would've been no rise of marxism across the world, no nazi revolution in Germany, no second world war and American domination of the world, and a strong Christian Empire would've stood guard over Europe.

And without the joojoo of Marxism, it would've been very difficult for the Jews to pass unpopular liberal policies like civil rights and feminism in the West. Americans by and large compromised on that stuff in order to unite against the allegedly greater Soviet threat. In a world where there was no Soviet Union, there probably would've been civil war in the US over desegregation.

Southern men back then still had balls and enough clout in the military to start an insurrection.