Actually, I would guess you could claim that true communists are the ultimate believers in the goodness of humanity. They believe that, if everyone is treated equally, with equal access to goods and services, without fear of hunger or illness, that everyone will work to their highest capabilities in order to preserve the common good.
In actuality, of course, it doesn't quite work out that way. Which is why the Soviet Union no longer exists, why China is branching out into a controlled capitalism, and why Cuba and North Korea, at least, can only survive as rigidly controlled dictatorships which ruthlessly (at least in the case of NK) hold down their populations.