What is the symbolic meaning of Giles Corey being pressed to death in Act IV of The Crucible by Arthur Miller?

The symbolic meaning of Giles Corey being pressed to death in Act IV of The Crucible reflects how he will not acquiesce to deceit.
Giles Corey is one of the most stubborn characters in The Crucible. Miller's physical description of Corey reflects many of the traits he shows throughout the drama:

Knotted with muscle, canny, inquisitive, and still powerful. . . He didn't give a hoot for public opinion, and only in his last years did he bother much with the church. He was a crank and a nuisance, but withal a deeply innocent and brave man.

Corey does not hesitate to speak his mind, as he does not "give a hoot for public opinion." Motivated by bravery and courage, Corey is passionate about truth. For example, he constantly challenges Putnam's motivations. Corey suggests Putnam's intentions are driven by greed for land more than spirituality. In his time in front of the court, Corey refuses to give into the pressure Danforth and Hathorne exert on him, acting as his own legal counsel. Corey is also pure of heart. He sincerely asks Hale questions about his wife's reading habits out of curiosity. He has no idea such questions could be manipulated into accusations against her. Throughout the drama, Corey actively avoids peer pressure. He will not be forced to do something unless he believes in it.
Corey's death symbolizes what he embodied throughout the play. Elizabeth's description of his death communicates how he represented his beliefs until the very end:  

He were not hanged. He would not answer aye or nay to his indictment; for if he denied the charge they’d hang him surely, and auction out his property. So he stand mute, and died Christian under the law. And so his sons will have his farm. It is the law, for he could not be con-demned a wizard without he answer the indictment, aye or nay. 

To compel Corey to talk, he was pressed to death. When he insists on "More weight," Corey challenges social pressure. Corey defiantly confronts authority's desire to get him to do something he refuses to do. By insisting on "more weight," Corey emphasizes that he will not lie or embrace deceit. His challenge for more stones emphasizes this refusal.
Corey was a devoutly Christian man. This is reflected in how Elizabeth says he wanted to die with his faith. In this way, Corey acts as a Christ-figure. His sacrifice shows the transgressions within the world around him. Corey's death symbolizes the injustice of the Salem Witch Trials and how resistance in the face of unrighteousness is the only appropriate response. By refusing to speak, Corey shows how goodness and one's word do not have to be sacrificed upon the altar of public pressure.