Quote 16
I felt him turning to look at me, and so I looked up. He had a particular expression which his face assumed when he understood but didn't think he should show it, a settled, enlightened look; its appearance now was the first decent thing I had seen in a long time.
He suddenly slammed his fist against the suitcase. "I wish to God there wasn't any war" (12.43-4).
What Finny hates isn't the war, it's the idea of a world he doesn't fit into. Finny may be all deity-like in the Summer Session at Devon, but he's ill-equipped to deal with the harsh realities of the adult world. And that's what he resents.
Quote 17
Bombs in Central Europe were completely unreal to us here, not because we couldn't imagine it […] but because our place here was too fair for us to accept something like that. We spent that summer in complete selfishness, I'm happy to say. The people in the world who could be selfish in the summer of 1942 were a small band, and I'm glad we took advantage of it (2.44).
"Selfishness" is an interesting interpretation of youthful naiveté. As we'll see later in the novel, Gene grows past this state – but Finny never does.
Quote 18
Everyone has a moment in history which belongs particularly to him. It is the moment when his emotions achieve their most powerful sway over him, and afterward when you say to this person "the world today" or "life" or "reality" he will assume that you mean this moment, even if it is fifty years past. The world, through his unleashed emotions, imprinted itself upon him, and he carries the stamp of that passing moment forever (3.42).
Gene claims that his "moment" is the war, but it is also his own state of enmity concerning Finny – his own private war and the emotions that go with it.