Several weeks ago my wife and I were driving home from Atlanta to Chapel Hill. A few miles out of the city, my eye caught a billboard featuring a lean young white woman pointing to her bare midriff. The caption read, "Look hon, no scars." The logo at the bottom directed viewers to the website of a local birth control clinic. Baffled (as usual) by the subtleties of modern advertising, I asked my wife what it meant. She patiently explained that it was an ad for tubal ligation. I drove on, thinking something deep like, "Oh."

After reading R. Marie Griffith's Born Again Bodies this past weekend, I saw the billboard in a new light. It is not often that a work of first-rate historical scholarship opens our eyes to the unspoken assumptions regnant in the world around us. But this one—written by a Princeton University religion professor—does. And no wonder. The book is exhaustively researched, elegantly crafted, methodologically self-conscious, and argued with moral passion. The volume marks a worthy successor to Griffith's influential Harvard dissertation on Women's Aglow, published in 1997 as God's Daughters: Evangelical Women and the Power of Submission.

The scope of Born Again Bodies is intimidating. Though focused on the American story, it begins deep in the Middle Ages and ends yesterday. In the process, Griffith ranges back and forth across the Atlantic, lingers among Puritans and their evangelical successors, delves into the intricacies of 19th-century New Thought partisans, ventures into the hermetic realm of body purging and fasting zealots, surveys a plethora of Christian-inspired sexual prescriptions and proscriptions, investigates the largely unknown sideroads of phrenology, physiognomy, and soma typing, and finally ends up in the vast subculture of the contemporary Christian diet industry.

Griffith's main argument can be stated in two sentences. Between the early 17th and the late 20th centuries, American body discipline practices evolved from a ritual of repentance to an exercise in self-gratification. Though a wide range of more or less secular forces propelled the process, Christians in general and white middle-class Protestants in particular pioneered that development. A closely related sub-argument is that Christians perennially have viewed the body as a window into the soul. Occasionally the process worked the other way around. A few body disciplinarians—usually New Thought advocates—felt that they could change the mind by manipulating the body. Either way, everyone, it seems, perceived an intimate connection between the spirit and the flesh. When it came to eternal matters, Christians saw through a glass darkly, but when it came to temporal matters, they saw clearly. The body told no lies.

Historians generally have interpreted the evolving meanings associated with rigorous dieting (and other kinds of physical denial) as a process of secularization. What started as mortification for sin, they say, turned into purposeful renunciation to compensate for the guilt of affluence and leisure.

Griffith disagrees. She argues instead that religion has been involved in those cultural protocols from beginning to end. The story is an evangelical one, centered on the good news of abstemious eating: go out, bring the (obese) sinners in, give them the (lo-cal) salvation message, hear their (before-and-after) testimonies, urge them to stay the (one-course) course, offer a helping (though never a second helping) hand to the weak-willed. If it is a New Thought story of gnostic discernment (there are bariatric secrets to be known), it is also a Wesleyan story of entire sanctification (permanent deliverance from the temptations of the palate), and a Reformed story of divine sovereignty (God's nutritional laws are non-negotiable). Above all, it is a millennialist story of can-do achievement. Our destiny lies within our hands. Just put down the fork and push yourself away from the table....