Subversion of Dystopia
A key theme of Leave the World Behind is the subversion of readers' expectations in an apocalyptic world. Throughout the genre and in popular culture, people in an apocalyptic world are portrayed to be in a state of constant chaos and uncertainty. By virtue of the character's geographical location (in a remote cabin) and because of their lack of access to resources, the characters in Leave the World Behind are not in a state of chaos. In fact, they are mired in a slow, banal process during which they fight to discover what is happening in the world around them, all while dealing with strange people.
Racism
Another major theme in Leave the World Behind is the damaging effects of racism. In the novel, for instance, Amanda does not believe that the couple that claims to own the cabin that she and her significant other had rented for a vacation belonged to them. Specifically, she doesn't believe that the cabin belongs to them because they are a Black couple. In fact, Amanda said: “This [cabin] didn't seem to her like the sort of house where Black people lived” because it was so nice and so high-class. This starts Amanda and the couple's relationship on the wrong foot, and understandably engenders some resentment between everyone. It also forms the basis for one of the major conflicts in the novel. That is: can these couples trust each other despite not having much information at their disposal?
Technology
A fairly significant theme in the novel is humanity's over-reliance on connectivity and technological devices. In the novel, each of the characters are members of society who rely on technological devices to give them needed news. When they don't have those devices at their disposal, the characters in the novel are lost and aren't able to fully function. Although they don't really know what happened (a pandemic, as it later turns out), the characters in the novel are left disabled by the lack of access to their devices and can't function fully despite needing to function fully.
