In the 1950s, why were Americans afraid of communism?
Americans were afraid of communism in the 1950s for two main reasons. First, communism seemed to be on the rise around the world, becoming more popular and more powerful. Second, since communism was an ideology, many Americans feared that it could infiltrate their country and turn people against democracy and capitalism.
By the 1950s, it appeared the communism was gaining strength around the world. In 1949, the Soviet Union had detonated its first atomic bomb, showing that it could compete militarily with the US. In that same year, the Chinese communists had defeated non-communist forces in their civil war. Communist North Korea invaded South Korea in 1950, leading to the Korean War, which lasted until 1953 and which came to involve China as well as North Korea. There were communist insurgencies in places as far apart as Greece and French Indochina. All of these things made it possible for Americans to think that communism was rising and becoming more powerful.
At the same time, communism was frightening because it was an ideology that could potentially appeal to people from any country. The US had never before fought against an ideology. Nazism was something of an ideology, but it was fairly specific to Germany and did not last long anyway. Communism, by contrast, explicitly claimed to be a universal ideology that could appeal to anyone. Because of this, Americans could worry that communism would infect their country. It would come in through communist sympathizers who would subvert American values and deceive the American people. Eventually, if these people were not stopped, they would make America become a communist country. Because of the fact that communism could sneak up on us, and because it seemed to be gaining power around the world, Americans feared communism in the 1950s.
The main similarity between the HUAC hearings and the Salem Witch Trials is that they were both conducted in an atmosphere that made it hard for the accused to defend themselves. In both cases, the trials/hearings happened at a time of great fear. People were afraid of witchcraft/communism and were inclined to believe that anyone accused of those things had to be guilty. In addition, both events involved people being accused of wrongdoing without any real evidence against them. They could simply be accused because someone had said that they were a witch or that they had once been a communist. In both cases, the people who were accused were very vulnerable because very little evidence was needed to support an accusation and because the general public was so afraid (of witchcraft or communism) that people simply assumed that the accused were guilty unless they could somehow prove otherwise.