This country did not always persecute people who belonged to the Communist Party. There was a time when people could join the Communist Party freely without terror and fear.
American People that joined the Communist Party generally did so in response to the Great Depression. During the Great Depression, the people that suffered horribly were not the rich, who already had a huge nest egg to live off of, but the working poor and the small working middle class. It was they who customarily joined the Communist Party.
Quite a few Jewish people joined the Communist Party when they became aware that millions of Jews were being savagely murdered in Hitler's fascist Germany, and that while Russia was fighting the murderous fascists, the U.S. was doing nothing about it. In fact, it wasn't until the German Ambassador officially declared the U.S. an enemy of Germany, that the U.S. even considered attacking Germany. By then, millions of Jews had been murdered, as well as Russians, and the German army was considerably weakened by the Russians.
The U.S.' wrongful executions of Ethel and Julius Rosenberg (in which the judge and prosecutors were constantly having ex parte secret meetings, the Rosenbergs were never found to have committed treason, and the judge's sentencing mentions that they were guilty of treason, which they were never found guilty of) took place because this country's government was being manipulated (as it is now) by corporations and the rich, into being terrified of Communists. The Rosenbergs were murdered because they were Communist, and scapegoats were needed to "teach" everyone a lesson about what would happen to people who chose to be Communist in this country.
I recently went to hear Robert Meeropol speak. He's an attorney; the younger son of Ethel and Julius Rosenberg. Fascinating speaker. I strongly recommend you all go see him whereever he is speaking. He also has a wonderful book: An Execution in the Family: One Son's Journey.
Here's an excellent and brief article explaining fascinating aspects of the Red Scare and America's expensive, expansive, and murderous widespread propaganda against Communism. The propaganda is still with us and I'm quite sick of it.
http://members.tripod.com/~HazelWolf/Hazel_Witchhunt.html