Religious imagery
The church imagery and cult imagery of the book defines much of the action in the plot. There are settings remembered, visual cues about cult attachment (like Adam's fancy pants). There are tangible reminders of cult behaviors, and there extreme states of religious dilemma in Tender's life. As his name suggests, he is sensitive to these cultish religious sentiments. Although it seems to explain itself, the reader will eventually have to question Tender's entire story—was he ever even in a real cult, or is all of this religious imagination of his own creation.
Suicidal imagery
Because Tender has a cell phone number that is similar to the suicide prevention hotline, he fields innumerable calls from the suicidally depressed. His (real or imaginary) cult revolves around ritual suicides. He is constantly being told of friends and family who committed graphic suicides, and the question of the novel is, how will he commit suicide? Many novels mention suicide, as it is a worthwhile question to explore for the purposes of harm reduction when it makes people feel alone, but this novel is thoroughly painted with suicide. It comes to the reader with the thoroughness of a plague.
The falling plane
We are reminded occasionally of the novel's real setting, an airplane cockpit. Tender is in a falling airplane, which he has hijacked and is now seeking to escape from. He will crash the plane, killing everyone on board, because he hates his (real or imaginary) sister who is on board the plane. For instance, he speaks this entire novel over the course of a few hours alone in the cockpit, talking to the black box. This imagery suggests the true horror of suicidal depression.
American nature
In the novel, we see interspersed in the stories scenes of Nebraska and Oregon, both very scenic states with their own "feel," one might say. The beauty and complexity of nature is a reminder of reality, which is important because of the man's very dubious grasp of reality. The juxtaposition of Tender's behavior and his sensitivity to the natural order is strange, suggesting a religious quality that he affirms in his own testimony. Also, he thinks he is a true American celebrity, which is a way of likening himself to a god of the land.
