Individuals predisposed to healthy-mindedness tend to ignore the evil in the world and focus on the positive and the good. James used examples of Walt Whitman and the "mind-cure" religious movement to illustrate healthy-mindedness in The Varieties of Religious Experience. In contrast, individuals predisposed to having a sick-souled religion are unable to ignore evil and suffering and need a unifying experience, religious or otherwise, to reconcile good and evil. James included quotations from Leo Tolstoy and John Bunyan to illustrate the sick soul.

William James' hypothesis of pragmatism stems from the efficacy of religion. If an individual believes in and performs religious activities, and those actions happen to work, then that practice appears the proper choice for the individual. However, if the processes of religion have little efficacy, then there is no rationality for continuing the practice.