This is a great book, whose flaw is that it leaves out the spiritual. It is striking to me that a book that was first published in 1928 would entirely omit God and even any reference to any saving or comforting thought of life after death. All is meaningless, brutish. The poor young men are in filth surrounded by death, under bombardment, expected to stand in line at the soldier's brothels, to take any pleasure wherever they find it. Athiesm has no comforts. What else but faith could have brought any meaning to their lives?
Remarque and later Tolkein, probably many other authors, portrayed people who have left home ( in their books the characters have left home for war). The characters have changed and can never quite fit in again afterwards, at least not ever in the same formerly comfortable way. Frodo in The Lord of the Rings is wounded by his struggle with the power of the ring, but he has a way out of his alienation. After a time at home in Hobbiton, Frodo departs with the last of the Elves from Middle Earth to a place of eternal life.
No comfort like that is available in Remarque's novel. Here is some of the prose Remarque wrote about that topic:
And even if these scenes of our youth were given back to us we would hardly know what to do. The tender, secret influence that passed from them into us could not rise again. We might be amongst them and move in them; we might remember and love them and be stirred by the sight of them. But it would be like gazing at the photograph of a dead comrade . . ..
To-day we would pass through the scenes of our youth like travellers. We are burnt up by hard facts; like tradesmen we understand distinctions, and like butchers, necessities. ...
We are forlorn like children, and experienced like old men, we are crude and sorrowful and superficial--I believe we are lost.
And the main character dies just at the end of the war. "Turning him over one saw that he could not have suffered long; his face had an expression of calm, as though almost glad the end had come."