On one hand, A Prayer for Owen Meany is a classic coming-of-age story, albeit with more than a few unique quirks and twists. The whole novel is narrated by John as an older man, reflecting upon the period of his life from early adolescence to early adulthood. Like so many other coming-of-age novels, we follow two friends – John and Owen – as they lose their innocence and start to understand the world in new and complicated ways. We see them develop from children to young men, and we witness the ways in which their perceptions of the world take shape.
Still, there's a lot more going on in this novel than the transition from childhood to adulthood. The novel moves along a very specific path, and this path is pretty much determined by Owen Meany's sense of mission and purpose. Owen is convinced that he is "God's Instrument," starting when he "accidentally" kills John's mother by hitting a foul ball that subsequently hits her in the head (we say "accidentally" in quotation marks because Owen, as you probably noticed, doesn't believe in accidents – everything, according to him, is meant to be the way it is). Owen knows that he has some specific duty to fulfill in his life, but he doesn't know exactly what it is – he only knows that he has a purpose. The novel takes us along on Owen's journey to figure out exactly how a bunch of disparate events in his life combine in order to create the one big moment through which he will fulfill his destiny.