An ideology is a rigid set of beliefs that defines what an individual or community thinks. In the Puritan theocracy of Massachusetts, a government run by religious authorities, the dominant ideology held that the Puritans were a chosen people that the devil would do anything to destroy. Since religious men ran their government, the Puritans considered all government actions to be necessarily "good," or sanctioned by Heaven. This meant that any attempt to question, obstruct, or otherwise resist any of the government's actions, no matter how ludicrous, destructive, or ill-informed, was considered by the government and other Puritans to be an attempt to overthrow God.
Governments fueled by such rigid and absolute ideological convictions often fall into corruption and tyranny without even realizing it. In The Crucible, Deputy Governor Danforth and Judge Hathorne believe that they're emissaries of God, and therefore that everything they believe must be true and everything they do must be right. They never see a reason to reassess their thoughts and actions, which makes them easy targets for cynical and talented liars like Abigail Williams. Characters like Abigail recognize the court's narrow-minded worldview and manipulate it to their own selfish advantage