I wouldn't try to approach this course material as something to debunk before I really understood what was being said. I went through the part about Marxist thought and it doesn't actually sound like your professor is trying to negatively portray Marxism or anything... Just putting it in context of other movements and not putting Marxism on a pedestal.
They are also focused more on what Marxism means for literary criticism rather than how Marxism can be used to affect society. Which is a valid way of approaching the topic.