VERY SPOILER HEAVY COMMENTARY FOLLOWS
Because this movie already has the factual stuff recorded in Wikipedia and IMDB, this review will instead concentrate on some of the themes and messages in the film. As such, heavy spoilers follow.
The movie is a 2004 comedy/satire produced by Michael Stipe of REM and starring Macaulay Caulkin, Mandy Moore and Jena Malone.
A brief plot synopsis, upon which to hang the rest of the review - it's senior year for Mary Cummings, one of the "Christian Jewels", a clique and high school assembly band at a Christian High School near Baltimore, Maryland centered around Mandy Moore's character, alpha female Hilary Faye. The high school is all manner of pop-Christian stereotypes, including hip "pastor Skip" with his son who's in the "Christian Skateboarding Association". Picking them all up in the new handicap van bought to ferry her paraplegic brother Roland, she pins "Christian Jewel" pins on the clique's chests, and they vow to make it the best year ever. The only problem (for Mary at least) is that through the kind of convoluted logic only someone raised since the age of three in a specific type of Christian expression could come up with, a combination of her perfect boyfriend "coming out" to her in a swimming pool, a simultaneous near-death drowning in which she's rescued by a Jesus-lookalike laborer, and the belief you can become a "born again" virgin if you don't have impure motives when you lose it (the latter is the result of a commentary by Hilary Faye on a Christian shooting range, of all places, as she puts repeated holes into the crotch of her target) she comes to the conclusion she needs to try and "rescue" her boyfriend from Hell and convert him to heterosexuality by sleeping with him.
Not only does it not work - at the beginning of the movie he is banished, near-wordlessly, to "Mercy House", where Christians shelve their embarassing wayward children (teen pregnancies, gays, etc.) for rehabilitation.
She's also pregnant, having been blessed with a lack of sex education until her school forced by the state to provide it.
She's pretty much alone in this, given her single mom (her father died when she was young) spends a lot of time at Christian camps and seminars with Pastor Skip.
She has a crisis of faith. Meanwhile Roland falls for Jewish outcast Cassandra, who everyone whispers was a stripper. Mary goes from being in the alpha female clique to hiding her growing pregnancy with frumpy and baggy clothes, aided and abetted by Cassandra and Roland who have seen her return from a Planned Parenthood. ("Why does a good Christian girl go to Planned Parenthood?" "To plant a pipe bomb?" "Okay, what OTHER reason...") She falls in with the outcasts, and arouses the ire of former friend/alpha bully Hilary.
After they get revenge on Hilary by posting a pre-surgery and weight loss photo of her around the school, she frames Cassandra and Mary to look like they've spray painted graffiti all over the school. During a search of their lockers, Mary's sonogram is found and her secret is out. Cassandra is expelled, and Pastor Skip urges Mary's mom to transfer her to "Mercy House", saying that in essence this is "God's punishment" for them getting involved with each other (he is in a loveless marriage but will not leave his wife because of evangelical hatred of divorce) in a shout-out to the story of David caught in adultery.
Roland finds out through credit card statements that Hilary was the one who bought the spray paint, so he decides the three will gatecrash the prom. So do the inmates of Mercy House, which causes quite a stir. Pastor Skip believes that Mary and Cassandra should be allowed in, as a Christian gesture of forgiveness, but the homosexuals and deviants do not belong. Hilary insists on their expulsion from the prom, causing Roland to produce the statements. In essence, that doesn't prove anything, because they had control of the credit card at one point as well. But one of the Christian Jewels found an actual Home Depot receipt in the car and produces that as proof, shocked to the core that she joined in on such a backstabbing clique. Hilary drives off and smashes the van into a painting of Jesus, and Mary goes into labor. A final family portrait, both of father and new boyfriend (Pastor Skip's son), mother and child, and assembled family and friends closes out the movie.
This is fundamentally a story trying to rescue the Bible and Christianity from the type of person that's usually seen as their champion - the slick, Crossroads Bookstore "What Would Jesus Do" Christian Rock loving white upper class Republican type. It's in essence a smackdown of the kind of holier than thou and purity code preachiness that has come to replace notions of forgiveness and grace.
Because, like the Bible, this movie is full of broken people. Cassandra is an outcast from just about everywhere. Most of the "Christian Jewels" are more about belonging and identity rather than in any sincere belief in Christian ethics - between Hilary "outing" Mary's boyfriend as a homosexual and trying to humiliate her by holding a condescending "prayer circle" for his salvation to Hilary outright sabotaging her own friend to get rid of someone she thinks is beneath her, her backstory shows just the level of insecurity and self-hatred that causes her to place herself above others. It isn't enough we see her fat, with bad teeth and a terrible haircut, her handwriting of DIE DIE DIE and NEVER AGAIN in jagged black pen strokes across the image clearly shows the scars over some deep pain. Mary, of course, sees how fast everyone turns on her and her boyfriend as soon as they fall from grace. Previously unpopular girl Tia, played perfectly to type by Heather Matarazzo - can be just as cutting and cruel to try to stay with the clique, but also finds a personal redemption in saying the right thing at the crucial time. Pastor Skip is doing what many women call "emotional cheating", on a woman who wants a divorce from him anyway. Roland is literally broken, and finds no solace in any kind of theodicy, being Christian in name only and openly being atheist. Christian Jewel Vanessa, adopted by two African Americans and originally from Vietnam, desperately tries to fit in to a very white, very upper middle class enclave and is more than willing to join in policing the community standard.