Water is Life: godless, by Pete Hautman (New York: Simon & Schuster, 2004).
Jason Bock is trapped in a fairly typical, godfearing midwestern town. On the spur of the moment he decides that water is so important that worshipping the water tower makes as much sense (if not more) as worshipping Christ. For him it's a joke. He recruits his best mate, the rather nerdish Shin, the violent, unpredictable but sf reading Harry, and a girl, Magda.
Things all come to a bad end. Harry breaks his leg, Magda chooses Harry instead of (as might be expected in teen fiction, the protagonist), and Shin tips over from weird to pyschotic.
Yet at the end Jason, ostracised, weired out and in debt up to his ears, is pretty happy and relaxed, having made the first step away from family and community.
This isn't an sf book as such, but both Jason and Harry are sf fans, Jason knows enough to reference Shin's obsession with snails to Sturgeons "Macrocosmic God" and the creation of the water tower as god, and the creation of the Chutengodians, is all done with a sharp eye to the Scientologists. This is a very knowing book, and the protagonists see themselves within a world in which sf exists (and you'd be amazed how often sf is absent from sf-nal worlds).