The Businessman is a well-conceived portrait of a world in which nature, humanity, and spirits are united into a system of existence that transcends the daily concerns of people. Even death is but a momentary blotch on a person's existence; from death comes new life in heaven. The only true death comes from the lack of imagination. In The Businessman, imagination is the key to understanding the universe. Through imagination, one may perceive wood nymphs, demons, and even spiritually advanced frogs. Indeed, the afterlife itself is defined by the imagination: "Heaven is no more than a fantasm generated by the excess energies of the pooled imaginations of the blessed."

Many themes are developed in The Businessman. In addition to the themes of a confused society, death, and imagination, Disch explores sexual and spiritual love, Christianity, dreams, and those traits that make people fully human. Unusual for Disch is the theme of hope. In most of his work, he creates satirical tragedies; the main characters are doomed to failure and death. However, the afterlife of The Businessman offers hope for eternal happiness. The afterlife can be just as terrible as Earthly life; spirits can suffer and live in purgatorial nightmares, but they always have the hope for advancement up heaven's hierarchy to the ultimate communion with God. Even the titular businessman, Bob Glandier may advance. He is grossly obese, small minded, and a murderer. He defines his entire life by his greed and eventually sells his soul to evil. Yet at the novel's end, he is in a purgatorial state that is not much different from what the spirit of John Berryman had to endure, and at the novel's end Berryman is in heaven. By inference, Glandier may also rise.