You can't argue with them, because they live by an entirely different logic. You come to a town where everyone's dressed all in white, for example. I'm thinking of a town we visited once just outside our usual territory, north of Kincardine, and then they tell you that they were saved from the Georgia Flu and survived the collapse because they're superior people and free from sin, and what can you say to that? It isn't logical. You can't argue with it. You just remember your own lost family and either want to cry or harbour murderous thoughts.
The passage reflects on the idea of encountering a community with entirely different beliefs and understanding. The speaker describes a town where the residents believe they avoided disaster due to their superiority and moral standing, presenting a perspective that is both alien and infuriating. This creates a sense of helplessness, as traditional arguments and logic seem ineffective against such convictions.
The emotional response of the speaker underscores personal loss and the struggle to reconcile those feelings with the indifference or arrogance of others. The juxtaposition of a rigid belief system and deep personal grief highlights the complexities of human experience in the face of contrasting worldviews.