Arthur Miller uses as his backdrop the Salem witch hunts of 1692 to create a parallel with what became known as "McCarthyism" in The United States. His intent was to suggest that if one does not conform to the will of the "powers that be" they could be highly vulnerable to the might of those very same powers. The reason why the people of Salem are vulnerable to conflict is because they may or may not agree with what is happening in their community, but know or at least feel that they are powerless to admit their true aspirations. The conflict lies in what the people believe and what they are "permitted" to believe.
In this play, Miller suggests that any kind of extremism and intolerance can be dangerous, and can lead to explosive consequences for everyone. The cultural climate of 1692 Salem was one of extreme religious intolerance, and many people who simply did not adhere to the narrow rules of the community were singled out for the accusation of witchcraft.
Not only did Miller base his play on the actual witch trials that took place in 1692, but on another shameful moment in American history. The play was written in 1953, at the height of the "witch hunt" known as the House Committee on Un-American Activities. This committee was led by Sen. Joseph McCarthy, and it accused many innocent people of having communist sympathies at a time when this was a very serious accusation indeed.
Miller's message is larger than historical events, however. The play examines the events of Salem to suggest that paranoia, irrational fears, false accusations, and the desire to blame others can only bring conflict, not resolution, to a community.