OK, it may seem like kind of a cop-out to name something that's not even a person as the antagonist of the novel, but let's take a closer look. It seems like most of the characters in the novel are pretty good people. We run into a couple of bad eggs along the way – Randy White, the headmaster at Gravesend Academy, antagonizes Owen during his high school years by censuring Owen's writing and eventually getting him expelled. Still, he's just a small blip on the radar – he comes and goes pretty quickly. Then there's Dick Jarvits, the angry teenager who attacks Owen at the end of the novel. Still, his presence in the novel seems to be a flash in the pan, too.
This leads us to scratch our heads and think a little more carefully about who and what an antagonist is. Who do our heroes, Owen and Johnny, battle against throughout the novel? We find that it's not a question of who, but rather what. Let's start with Owen. Owen has some major beef with the Catholic Church because of an "UNSPEAKABLE OUTRAGE" that the church purportedly committed against his parents. Then again Owen also has issues with the Episcopal Church because he thinks that the design of the services interferes with his ability to pray. Owen also takes on the whole system of Gravesend Academy, finding fault with its practices, traditions, and rules. He rails against various faults of the Academy in his column for The Grave, for which he writes under the pseudonym "The Voice."
John's enemy, likewise, isn't just one person; it's the entire United States of America. John leaves the US in 1967 and moves to Toronto, but he continues to obsess over what he considers to be the country's faults. He's bitter about Vietnam; he's angry at the current Reagan administration (remember, we're in 1987 here); he feels like there is too much deceit and lying. John regards the United States as a corrupt and depraved country, and to him, even Canada isn't far away enough.