Have you ever read “I Led 3 Lives”? Not the book for the TV show of the same name, but the autobiography of the man who infiltrated the communist party in the United States. He was a anti-war guy at first, though not a communist, who got sucked into it before he realized they were indeed communists and soviet agents. He approached the FBI and was encouraged to stay with the group and gather information.
According to him, it seems the communists literally infiltrated most of the institutions in the United States. From churches all the way to the medical industry. You’ll see big names like the ACLU, before they were known for what they are known for today, who at that time were targeted by the communists for take-over.
There is a YouTube video where he explains the nature of communism and its infiltration of U.S society. He’s a man’s man, though I’m too lazy to go to my bookcase so I can get his name. If memory serves, it is Herbert Philbrick.