In the Season 7 episode ‘Bart Sells His Soul,’ Bart and Milhouse get into a theological discussion (rather advanced for a pair of 10-year-olds) about the nature of the soul. Milhouse whole-heartedly believes in the concept of the soul as presented by organized religion, while Bart maintains that the soul is fake, made up by religion to manipulate the masses and make a profit off of tax-free donations. And he’s entitled to that opinion.

You know who’s not okay with that? Lisa.

While Lisa is generally portrayed as a liberal free-thinker, supporting the rights of the oppressed, her actions in this episode greatly contrast those character traits. Once she finds out that Bart sold his soul to Milhouse (it was actually just words written on a piece of paper), she is clearly disturbed by the fact that Bart doesn’t take the concept of the soul seriously. She presses her own agenda upon him repeatedly, and mocks him in front of their family for his beliefs.

Because she disagrees with Bart’s opinion, she ostracizes him, and uses a series of arbitrary coincidences to convince Bart that he has lost his soul. She even buys his soul when she finds it in the Android’s Dungeon comic book store, and then proceeds to withhold it from him. It is only after he goes through Hell, is missing all night, and comes home in a clearly broken state, that she concedes and returns his soul to him.