The underlying concept of a better society with the rights of workers paramount might b a tad simplistic, but is fundamentally a form of utopianism. Naive and impossible in practice, but I don’t see how it is inherently evil. And really, when you look at how workrs were treated in Britain in the mid-19th century, when Marx and Engels were developing Communist political and economic thought, you can’t say there wasn’t some justification in the observation that the working classes of Britain (and to one extent or another just about everywhere else) were being abused and exploited. Communism wasn’t the answer, but it did ask some fairly important questions.
And yet Marx’s theory never set out to kill millions. That may have been an inevitable consequence of Communism, but unlike Nazism, that was never the intention. Read Mein Kampf and tell me Hitler had any kind of noble, if deeply misplaced, higher goal.
And still, even with Communism producing the misery it did, that doesn’t mean Antifa is Communist, so it really is just you trying to create a moral equivalency. Antifas is mainly just a pack of naive kids who, like those that came before them, going back eighty years, want to thump some fascists.