Poking at the Obvious: Democracy and Communism

I suddenly realized a few years ago that vocalizing what seems obvious to me can help me bring analysis into my texts (this is something I tell students, though it works better for those with a strong foundation in reading who need a push to figure out how to write the analysis they are already doing in their head, rather than the students who need help analyzing at all). I'm learning this all over again as I edit my dissertation. I'm also realizing that analysis can sometimes begin when one pokes at something that seems obvious or taken for granted.

For example, consider the relationship between democracy and communism. What associations do those two words immediately conjure for you?

In W. E. B. Du Bois: Black Radical Democrat, Manning Marable writes

Even Du Bois’s costly decision to defend the Communist party during the period of McCarthyism was both a political and a moral act. He would affirm his basic faith in democratic principles, even if his government would not.

Anti-communists fought communism because they saw it as a threat to democracy (i.e. overthrowing the American government. The CP listening to dictates from the USSR). Many intellectuals fought for communism because they thought they were protecting democracy (either in an economic way or in the way of free speech). I've always wondered a bit how a Communist Party functions as a political party in a democracy. It seems like a group focused on socialism and gradual change would make more sense than a revolutionary party. But maybe that is because revolution is not in fact as important to Communists as I think it is. Or to some communists, at least.

What do you think? Is there a conflict here? What is the relationship of communism and democracy?