Cultural Marxism ... a buzz word by the far right wing. Where does it come from?
It was in the starting years of the 90s in the US, as the Red Scare didn't work anymore as enemy-picture, in the west, but just mainly in the USA (you know Gorbatschow etc. breakdown of the real-communism/real-socialism ... Warshaw-pact).
The far right, or better said, the new right in the american political spectrum, in the US the right wing of the Republicans needed something new to blame. A book was also written at the time called 'The Death of the West' iirc., which put some fire into it.
The new thing for the new right, first in the US (far right, if you want) was then the religious-cultural war against everything that is moderate-liberal-social-democrat politics aka liberal values, all that idiocy led then to the Tea Party wing within the Republican party.
It has its roots in the McCarthy-time, where american apparent-leftists were persecuted, and that also goes back to the time, as european rather german philosophers emigrated into the US (refugees of the Nazis), and became professors at american universities, ie. the men of the so-called Frankfurter School, who also where a source of the 60s students revolt and overall the change of politics rather culture in the end 60s, first in the US, then in europe.
Back then to the 90s, the time of the new right. It was the time of somebody called G.W. Bush, and the time of the evangelical movement there.
Europe's right wing, in most of those reactionary things a step behind the US, practically kept over that new enemy-picture, with the growing EU et al as main enemy.
Just nowadays, the reactionary right wing in europe uses the term Cultural Marxism (which has its origins in the US) to blame populistically the process that happens in euope's political stage, within the single nations and especially for the EU government and its politics.
As Napoleonic Bonapartism (poster above) rightly called it, a pan-western tendency of a new right wing, which gained (esp. since the 90s) and gains currently political power, underlined by an overall valid tendency to more conservatism aka new national-conservatism, in comparison to the end 60s, 70s and 80s ... in the latter decade, that tendency started.