Douglas, a former minister, wrote Magnificent Obsession to update Christian principles for a generation that considers itself too objective, too scientific, and too modern to accept Christianity couched in traditional religious rites and observances. By selecting the medical profession for his setting, he brings the religious debate into an arena known for its practicality and usefulness to humanity, as well as into one in which scientific principles are recognized over superstitions or sentimental concerns. His protagonists are shown to be modern scientists, skeptical and grounded in common sense. Only after being shown evidence of the pragmatic results of applying Christian principles are the protagonists convinced that the teachings of Jesus have value. Moreover, these teachings are demonstrated to deliver substantial, tangible benefits to those who practice them to provide motivation for those who wonder what is in it for themselves.

The New Testament source for Hudson’s “secret formula” is described in the novel but never actually quoted, obliging readers to find it themselves. The buildup of suspense is designed to bring readers to the Bible, where they must read and search for the “secret formula,” thereby becoming more acquainted with the teachings of Christ as they discover the key to personal power. The secrecy emphasized in the novel adds excitement and a feeling of adventure for readers who might otherwise pass over admonitions to do alms in secret so that they may be rewarded openly.

The stories of Bobby Merrick and the others who change from ne’er-do-wells, drunks, and despairing failures to become admired, prosperous, and happy successes serve as anecdotal evidence to convince readers that following Christian principles of service, forgiveness, honesty, and charity will lead to real, earthly benefits not only for the recipients of good deeds but also for the doers.

A final theme of this novel is the change in religious vocabulary represented by Douglas’s attempt to couch Christian doctrine in new, scientific terms that will attract modern readers. Those who reject the ideas of repentance and atonement for sin may want to “restore dissipated personality” or “recover energy” instead. Those eschewing traditional topics such as salvation, redemption, heaven, and hell may be interested instead in “personality projection,” “having anything you want,” “turning the key to personal power,” and “the principles imperative to an expanded personality.” This novel’s popularity testifies to its readers’ interest in updating Christian terminology and to its author’s success in presenting Christian charity and service as not only relevant to the modern world but also essential in achieving a happy life within it.