"I am not sure I can imagine Marx making the kind of remark that Epicurus made in the letter to Menoeceus about it being better to believe the myths of religion than the views of hard determinism." You are spot on with this one. Marx' historicism is a kind of hard determinism. Different from the passivity of other proponents of determinism, Marx recommended betrayal of democracy and gross atrocities in order to accelerate establishment of communism as the predetermined end state of history.
I compared the section quoted by Joshua with what I guess is the German original and found the following mistakes in the translation: "..., which is an inverted consciousness of the world, because they are an inverted world" is only formally correct. The German adjective "verkehrt" translated here as "inverted" should be translated here as "wrong", and with that meaning, the phrase makes more sense: "..., which is a wrong consciousness of the world, because they are a wrong world". "..., weil d…