system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What exactly did it mean to be communist in the US 50 years ago? Why the hell was it so unspeakably bad?

Studying it in history class, i'm not following this.

**UPDATE:** I got the point minutes after posting, but these responses show no sign of stopping. I think I know more about Communism now than my professor...

Regardless, you guys are great! I'll be posting her more often!
gpt
Remember the Soviet Union was considered an existential threat to America.  It would be similar to declaring yourself an Islamic jihadist in modern-day Western society.  You can make the argument that the ideology isn't inherently bad (jihad means "holy struggle", etc.), but don't expect a lot of sympathy from the public or from law enforcement.