In the episode, "The Father, the Son and the Holy Guest Star", Springfield's only known pastor, Reverend Timothy Lovejoy, states that his church (and that of the majority of Springfielders) is actually part of "The Western Branch of American Reform Presbylutheranism". This episode also makes a Unitarian reference when Homer Simpson asks if he needs to "wail on a few Unitarians" to become Catholic. Many of the characters in the show are negatively neutral to openly hostile toward Unitarianism. Another example of this would include Reverend Lovejoy offering the Simpson kids a bowl of Unitarian ice cream at a church social function. When Lisa remarks that the bowl is empty, Reverend Lovejoy indicates that that is the point.
The most religious characters on the show are Ned Flanders and Reverend Lovejoy. Flanders appears to be conservative Christian and appears to express little tolerance to other faiths and sexualities (mostly pagans, Jews, Hindus and homosexuals), claiming they are all hedonistic, and those who follow said beliefs will go to Hell. Lovejoy seems to resent the fact that the Doctor Julius Hibbert's family joined the First African Methodist Episcopal Church of Springfield, while Ned tells Apu, who is a Hindu, that he might as well be praying to Hawkman. In one of the episodes, the Hindu god Vishnu is shown as sitting in the center of the earth and controlling the world with a whole lot of levers. There are also numerous references to the Hindu god Ganesh, mostly by Homer when interacting with Apu. In another episode, Rev. Lovejoy says to Ned Flanders, during an annoying phone call: "Ned, have you considered any of the other major religions? They're all pretty much the same."
Excluding the odd reference by Kent Brockman to "churches, synagogues and mosques," condemning Krusty the Clown for corrupting the young in one episode, the religion of Islam or Muslim characters were not featured heavily in the series until the episode "Mypods and Boomsticks.". However, in the episode "Marge Simpson in: 'Screaming Yellow Honkers'", Homer proclaims, "I'm gonna die! Jesus, Allah, Buddha, I love you all!" when fearing for his life. In "The Seven-Beer Snitch", the Simpsons go to see "Song of Shelbyville". There is a lyric in the main song which says that Shelbyville is home to Christians, Muslims, and Jews "although not many of the last two". This makes a Rabbi and an Imam in attendance feel uncomfortable. The episode "Grift of the Magi" has Krusty touched upon all religions by saying, "So, have a merry Christmas, happy Chanukah, kwazy Kwanza, a tip-top Tet, and a solemn, dignified Ramadan." Also, in The Simpsons Movie, when Rod asks Ned if Buddha will be with Jesus in Heaven, Ned angrily says no. Ned is implied to hate Judaism.
The Western Branch of American Reform Presbylutheranism
- Main article: First Church of Springfield
- Main article: Movementarianism
Episodes with significant religious content
- "Homer vs. Lisa and the 8th Commandment" - Lisa gets mad at Homer on religious grounds for stealing cable.
- "Homer the Heretic" - Homer stops going to church.
- "The Joy of Sect" - Homer and most of the family join a religious cult.
- "Faith Off" - Bart becomes a faith healer.
- "She of Little Faith" - Church gets destroyed by Homer's Do-it-Yourself rocket. Using this opportunity, Mr. Burns buys the Church out and turns it into a commercial asset. Upset by the "materialization" of Church, Lisa leaves the Church and decides to become a Buddhist.
- "Thank God It's Doomsday" - Homer becomes convinced that the Rapture is nigh.
- "The Father, the Son and the Holy Guest Star" - Homer and Bart become Catholic after Bart was expelled from Springfield Elementary from tantalizing a medieval festival at his school (which he actually did not do which was really caused by Groundskeeper Willie who was the one should be fired before he was later welcomed back as an apology) and is subsequently enrolled into a Catholic school, where he is drawn in to a comic book about the Saints.
- "Simpsons Bible Stories" - The family daydream their own interpretations of stories from the Bible.
- "Today, I Am a Clown" - Krusty holds his bar mitzvah.
- "Simpson Christmas Stories" - Homer tells the story of the first Christmas.
- "The Monkey Suit" - Ned forces the school to teach creationism instead of evolution.
- "Like Father, Like Clown" - Bart and Lisa attempt to reunite Krusty with his rabbi father who disapproves of his profession.
- "Bart Sells His Soul" - Bart sells his soul to Milhouse in the belief that it is not real, then later realizes that he can't function well without it and tries to get it back.
- "Lisa the Skeptic" - Lisa finds skeleton bones what appears to be an angel, and everyone in town (except Lisa) believe that it is an angel.
- "Pray Anything" - Homer finds that everything he prays for comes to him. After praying for a new house, he is accidentally injured on church property. Homer sues the church; he is given the deed to the church and turns it into his new home.
- "I'm Goin' to Praiseland" - Ned builds a Christian amusement park by Maude's vision. It is very boring but when a miracle occurs, it quickly becomes popular.
- "Kiss Kiss Bang Bangalore" - When Homer stars work for Nuclear Power Plant in India, with "help" from a book he becomes popular and starts to rule the plant like a god.
- "Mypods and Boomsticks" - Bart befriends Bashir bin Laden and Homer learns to become tolerant of Islam.
- "The Greatest Story Ever D'ohed" - The Simpsons visit Israel where Homer develops Jerusalem syndrome.
- "Ned 'N Edna's Blend" - Homer portrays Jesus in a passion play to the dismay of Flanders.
- "Pulpit Friction" - Lovejoy is replaced by a new minister.
- "Clown in the Dumps" - Krusty becomes a more observant Jew after the death of Rabbi Hyman Krustofsky.
- "The Nightmare After Krustmas" - Krusty briefly converts to Christianity in order to bond with his daughter Sophie Krustofsky who was raised Christian.