What are some allusions in "The Crucible"?
In Act Two, when Francis Nurse arrives at the Proctors' house, he tells John and Elizabeth Proctor, Mary Warren, and Reverend Hale that his wife, Rebecca, has been accused of and arrested for witchcraft. The Proctors are in shock, but Reverend Hale still wants to believe in the justice of the court. He tells John, "in great pain," that "until an hour before the Devil fell, God thought him beautiful in Heaven." Here, he alludes to the angel, Lucifer, and his rebellion against God. Hale says that, until right before Lucifer fell from God's grace, God still thought him to be good. In other words, it is possible that Rebecca seems good, or has been good all along up until now and that she has still fallen and committed this grievous sin.
Also, in Act Two, when Herrick comes to arrest Elizabeth Proctor, John tries to make Hale see that the court is not just—that the girls are not honest. He shouts, "Pontius Pilate! God will not let you wash your hands of this!" Here, he alludes to Pontius Pilate, the Roman governor of Judea, who did not think that Jesus deserved to be executed. However, the crowd called for Jesus's crucifixion and Pilate gave in to them, symbolically "washing his hands" in order to show that he did not consider himself to be personally responsible. However, in doing so—allowing a man he believed to be innocent to be killed—history has judged Pilate to be just as responsible, if not more so, than they. John calls Hale "Pontius Pilate" because he believes that Hale is trying to keep his own hands clean, so to speak, by allowing a corrupt court—just as Pilate allowed a corrupt crowd—to make all decisions concerning the innocents who are accused.
Most of the allusions are biblical in nature. Take for example what Elizabeth says about Abigail's power in the town after the accusations are starting. In act two, Elizabeth states, "Abigail brings the other girls into the court, and where she walks the crowds will part like the sea for Israel." This is referring to Moses, who parted the seas of Israel for the Israelites to escape from the Pharoah's armies. So, it indicates that Abby holds some sort of god-like power of redemption for the town. Another allusion to the bible is when John Proctor is trying to help Mary gather courage to confess to the courts that the girls are faking. In act three he bolsters her saying, "Now remember what the angel Raphael said to the boy Tobias...'Do that which is good, and no harm shall come to thee.'" He refers to that quote to help her to have strength to do what is right. Reverend Hale alludes biblically to Satan, and how "until an hour before the Devil fell, God thought him beautiful in Heaven." He is speaking of how it is possible that Rebecca Nurse could be charged with witchcraft in act two.
Because of the Puritan beliefs that the bible is all, the people were very familiar with its stories and morals, and that is probably why Miller chose to it as the main source of most of the allusions in the play. I hope that helps!