Lisa abandons her Christian faith (after the local church sells ad space inside of it to cover the damages done by Homer and Bart's toy rocket) and opts for a new one that still allows her to be close to God, Buddhism. When words gets around, Marge tries to win her back to Christianity, but Lisa refuses.

!!Tropes of this episode:
* AdHominem: The criticisms of Christianity in this episode, including Lisa's crisis of faith and conversion to Buddhism, hinge on this trope. The catalyst and case for them are the actions of a few Christians; Reverend Lovejoy and the congregation compromising by allowing [[CorruptCorporateExecutive Mr Burns]] to fund the church and dictate its layout. God's existence, nature, authority, and the merit of His teachings is not touched upon at all, thus making it a very selective criticism.
* {{Bowdlerization}}, WordOfGod, and WhatCouldHaveBeen: Originally, there was supposed to be a scene where an Arab man named Hassan Jay Salam is arrested for shooting the rocket into the church because the rocket has his initials on it (which are actually Homer's initials), but, because of the 9/11 attacks and fear of backlash from Arab viewers, the producers had the scene cut. The DVD commentary talks about the missing scene, and it is included on the deleted scenes reel on the DVD.
* BrokenAesop: Christianity is criticized a lot during this episode, while Buddhism is presented in a more positive light, almost as if it is the best possible faith one could have. Furthermore, Lisa criticizes her local Christian Church for having become too commercialized and joins another religion, only to return soon afterwards, because she just can't miss her Christmas presents. This is hypocritical for a number of reasons: 1) Buddhism, just like any organized religion has both good and bad aspects. Not mentioning or mocking those at all is ''very'' one-sided. 2) As much as Lisa criticizes her local Christian Church, the problems are minor and hinge on the compromise of part of the congregation and she joins it again without much fuss. 3) She criticized the local Church for being too commercialized, then joins it again out of the same materialistic greed as the other churchgoers she formerly criticized.
* CallBack: Benjamin, Doug and Gary from the episode "Homer Goes to College" have a cameo.
* CrisisOfFaith: Plot of the episode.
* GracefulLoser: Burns tries to disappear in a smoke bomb with the benefit the church made plus his initial gain. When he fails reaching the door in time he just throws all the money at the church committee. No one even tried stopping him he was just disgusted his escape failed.
* JerkWithAHeartOfGold: Kearney, a known bully and petty thug, is right to point out what has to be done about the church, making it a priority.
** Burns also fits this trope; after all he did help rebuild the church, even if the advertisements inside were in bad taste. Subverted in that he actually wanted to make a run for it with the profit the church made but when he failed he ended up being a GracefulLoser.
* KidHasAPoint: Lisa does explain to Bart she's not going for a new way to worship just because it's sounds cool, she rather find one that brings her peace while reminding God that she still respects Him.
* MoralDissonance: At the start of the episode Lisa leaves her Christian faith because she feels her local church has become too commercialized. She then become a Buddhist, but is confronted by a dilemma because her parents try to lure her back in by celebrating Christmas (in the incorrect notion that this feast is exclusively a Christian holiday: the feast itself was already celebrated by pagans centuries before Christianity claimed it). Lisa likes celebrating Christmas, but at the same time she wants to stick to her Buddhist beliefs. Then Richard Gere informs her that while Buddhism is about one finding inner peace, it is also about respecting the diversity of other religions based on love and compassion - thus, Lisa is free to celebrate any holiday with her family including Christmas. So... when you think about it: Lisa now more or less joins Christianity again for the same reason she originally abandoned it: [[BrokenAesop she just wants to have her Christmas presents and take part in a holiday celebration that has become increasingly commercialized in recent times! ]]
* OutOfCharacterMoment: Marge is very intolerant of Lisa leaving Christianity and joining Buddhism, while Homer isn't particularly bothered by it.
** Lisa herself also acts out of character here. In ''Homer the Heretic'' Homer felt going to Church was a waste of time, but raised some excellent thought provoking points about it. Despite that Lisa shunned him for doing so. In this episode Lisa is the one having good reasons to leave the increasingly commercialized Church of Springfield and not wanting to go to Church anymore. The odd thing is that she has criticized the local Church before, but usually separated this from her genuine belief in God. Now she seems to have put the two together and chooses for another religion, though one could raise a lot of similar critical points about Buddhism as one could about Christianity.
* PetTheDog: Even though he opts for commercialism, Mr. Burns does live up to his promise to help rebuild for the church. Granted his plan was to prostitute the church and run with the money it made but he didn't fight hard when his escape failed.
* RecognitionFailure: Despite being a Buddhist Lenny astonishingly has no idea who the Dalai Lama is, nor Buddha.
* SpecialGuest: Richard Gere as himself.