There is a great book, “Leftism Revisited: from de Sade and Marx to Hitler and Pol Pot” by Erik von Kuehnelt-Leddihn that was published in the 90’s that discusses the history of leftism and it’s destruction. It’s out of print, but if you can get you hands on a copy it is worth reading.
That is an epic and scholarly work. Fortunately, I purchased a copy a few decades ago.
"And, as pointed out earlier, the majority of those belonged to the leftist camp and were soon intimately tied to the American Left. More often than not, these men had previously helped undermine the fabric of traditional Christian Europe, creating the frightful void that communism, socialism, and later National Socialism would fill. Deserted altars are inhabited by demons.”
Thanks for the book recommendation, I’m going to try to find it.