Like Reverend Hale and the others on this stage, we conceive the Devil as a necessary part of a respectable view of cosmology. Ours is a divided empire in which certain ideas and emotions and actions are of God, and their opposites are of Lucifer. The concept of unity, in which positive and negative are attributes of the same force, in which good and evil are relative, ever-changing, and always joined to the same phenomenon – such a concept is still reserved to the physical sciences and to the few who have grasped the history of ideas.
– Arthur Miller
The Crucible, Act 1. In this explanation, Miller says that we live in a divided world of extremes, black and white, positive and negative forces that constantly oppose one another. One side sees their ideas and actions as being of God, and those of the other side being the work of the Devil. The author is touching on the themes of good vs evil and intolerance in this passage. Miller is saying that good cannot exist without evil, and vice versa. He is providing the context in which religion and politics are played out in the rigid Puritan society of Salem, where if you are not seen to be with God you are with Lucifer. The 1950s McCarthyism is also seen here, the play being an allegory for the Red Scare led by Senator Joe McCarthy in which people were unjustly hounded over their supposed communist loyalties.