The deteriorating social environment depicted in Carpenter's Gothic contributes significantly to one of its major themes. In such a world where nothing goes well, how can individuals find solace or meaning? The answer, in Carpenter's Gothic, is that they do not. One of the main characters, McCandless, reads his fate in a book (V. S. Naipaul's Mimic Men): "A man, I suppose, fights only when he hopes, when he has a vision of order . . . . But there was my vision of a disorder which it was beyond any one man to put right." McCandless's bleak vision has been seen as representing Gaddis's. References to the apocalypse and Armageddon toward the end of the novel indicate that there is nothing whatsoever that follows this meaningless earthly existence — and if that is the case, all the events of the novel are rendered insignificant.

One related theme would be that, in a world where there is so little hope, truth becomes a slippery entity. Ambiguity, introduced in the very first line of Carpenter's Gothic — "The bird, a pigeon was it? or a dove" — prevails. In a complex post-modern world, nothing seems clear-cut.

Another related theme is how the distortions of Christ's message by modern-day Christians have led to an absolutist mentality that has contributed greatly to the diseased state of present-day society, resulting in the kind of self-serving Bible-quoting heard from Lester, and the cold war ideology espoused by the president in the New York Post headline appearing at the novel's (and perhaps the world's) end: PREZ: TIME TO DRAW THE LINE AGAINST EVIL EMPIRE.

One last theme would be a focus on the creation (and again, the worth) of fiction, here depicted through McCandless.