What is the importance of fire and other symbols in the development of the theme?
Fire consumes the church where Johnny and Ponyboy have been hiding out after Johnny kills Bob in an act of self-defense. As they are leaving the church, they notice it is on fire, and Ponyboy feels guilty because he thinks they started the fire by smoking cigarettes in the church. They notice schoolchildren are trapped in the fire and rescue them, but Johnny is badly injured while doing so. The fire symbolizes the destruction of innocence, as the church is a symbol of innocence (particularly the schoolchildren who are in the church). The fire also symbolizes their rebirth, as it symbolizes the phoenix, a mythological bird that is reborn out of fire. After the fire, Ponyboy and Johnny are no longer outcasts or criminals who are hiding from the law. Instead, they are reborn as heroes, and Ponyboy is united with his brothers. The symbol of fire and its association with rebirth supports the theme of Ponyboy's rebirth as a promising writer and loving brother.
Often times, literature uses fire as a symbol to represent an ordeal or trial, much like the phrase "trial by fire." When the characters in The Outsiders face the fire in the church, the moment becomes an opportunity for them to prove themselves and find their self-worth. Fire has the power to strip everything away to reveal what lies beneath, like metal in a crucible that is set into the fire to remove all the impurities. Much of The Outsiders deals with appearances and how outward appearance shapes perception. In the scene with the burning church, the fire effectively stripped away 'the greaser' persona from Johnny, Ponyboy, and Dally; they ran into the burning building to save the lives of children but emerged as heroes.