This quote stated by Mary Warren, how does it portray symbolism (regarding the witches trials and McCarthyism) and the significance:
“What’ll we do? The village is out! I just come from the farm; the whole country is talking witchcraft! They’ll be callin’ us witches, Abby!" (Act I in The Crucible)
The presence of fear and innuendo that seems to be infecting the village is an excellent way to describe the Red Scare that followed World War II. The notion of "the whole country is talking" helps to bring to light the idea that individuals in the position of power are able to maximize the public fear and paranoia to consolidate their own power and their own sense of control. The fear of what others will do is something that members of the town in the position of power are able to use to their own selfish benefit. This is similar to McCarthy and others in the government that were the direct beneficiaries of American fear of Communism and the fear of being called a "Communist."
The significance of this quote is that it shows Mary Warren and Abigail Williams talking about how they fear they are going to be labeled as witches. This is important because we know that they will turn around and start accusing others so as to avoid being called witches themselves.
You can say that this symbolizes the way that people acted during the McCarthy Era. You can say that people figured that if they accused others of being communists, then they, themselves, would not be suspected.
So, you can see this as a symbol of how fear makes people act.
McCarthy ran the House Un-American Activities Committee. Many Americans at that time were sympathetic to the communist movement, people are always enticed by that which is different. McCarthy was fearful that these folks would spread their beliefs and thoughts and infect American culture which had been built on something so different than Communism.
Miller saw that this act of McCarthy was like crying 'wolf.' After choosing to write about it, the best parallel he came up with was the era of the Salem Witch Trials. McCarthy must have used dramatic propaganda to get many people talking about this anti-American attitude.