Today is "May Day", labor day for most of the rest of the world, and a day of remembrance and celebration for communists in particular. On this day in 1886, nationwide strikes in Canada and the United States were called to protest the lack of a mandated 8 hour workday. In Chicago police killed six protestors trying to break up the strike. The next day seven police were killed in a bomb explosion. Eight "anarchist trade unionists" (establishment-speak for "noisy, effective leaders") were arrested, but it has never been conclusively established who was to blame. In spite of this, the men were tried and executed in what nearly everyone now admits was a kangaroo court of the worst sort. A more detailed account of what happened is here.
Communism is a very poorly understood system in the US. Because those who hold the reigns of power over here are pretty much by definition capitalists, and because labor drives capitalism, it isn't in powerful people's best interest for anyone to think any good of communism, which at its roots seeks to empower labor against management. Historically communism has proven quite good at this, at least in the short term. Nothing shakes a rich, powerful man (and they're almost all men) quite like threatening his money, and so communism became demonized like really no other idea in history. The origins of WWII are rooted in the fact that the west feared the Soviet Union far more than they feared the Nazis.
The reasons for the failure of communism are many and varied, but the basic concept is actually a lot simpler than you're lead to believe in your high school history courses. Instead of learning about Karl Marx, "owning the means of production", or, *shudder*, actually trying to read Das Kapital, communism can actually be summed up in a simple sentence:
In a true communist system, everyone owns everything.
So what would living in a true communist society be like? Well, you wouldn't need to buy a house, you'd just need to move into an empty one. And it wouldn't be empty either, because it would've already been filled with furniture. You don't have to buy a car, because there's dozens of them parked in the lot with the keys inside, just waiting to be driven. Need new clothes? Just go to the clothing outlet and grab some shirts. Hungry? Walk up to a counter and grab a sandwich. Need something to do? Find an empty space on a factory line and pitch in.
Of course, there are really obvious problems with this, mostly to do with human nature rather than any real flaw in the idea of communism. I sometimes think that Karl Marx and Friedrich Engles typify the axiom that some ideas are so wrong that only an intellectual will believe in them. Communism gives "gamers" so many seams to exploit that they're just overwhelmed. This was proven to be true when good ol' Uncle Joe (Stalin) clawed his way to power and transformed the workers paradise into an old fashioned dictatorship in just a few years. Pretty much every other attempt at this ideal has run into the same wall of cheaters and sheer human laziness.
The only really fundamental flaw I can see in communism is that, to really work, it requires free energy and robot labor. If it doesn't cost anything to make stuff, then stuff can be free. If it doesn't take people to make stuff, then stuff can be free. Ironically, capitalism's constant striving for more and more efficiency and cheaper and cheaper labor could end up delivering us to the communist state.
But really, that's all there is to communism. No attempts on the "american way of life", no "institution of athiests", no "evil empire"... just a bunch of idealists with a really bad understanding of how real people tick. To quote a favorite movie of mine, "anyone that tells you differently is selling something."