This article explores the phenomenon of nineteenth-century new religious movements as a reaction to the “plain Bible” religious culture of that era. The plain Bible thesis maintained that the Bible was clear in its meaning, persuasive in its message, and authoritative in all matters of truth. Through the examples of Joseph Smith, Mary Baker Eddy and Henry David Thoreau, this article illustrates how three religious innovators reacted against the plain Bible thesis by creating their own versions of scripture which, in turn, aided in creating or strengthening alternative forms of Christianity. With his Mormon scriptural canon, including The Book of Mormon, Doctrine and Covenants, and Pearl of Great Price, Smith combated the notion that the Bible was clear in meaning; with her sacred text Science and Health Eddy challenged the persuasiveness of the plain Bible; and with his manuscript Wild Fruits, Thoreau undermined the plain Bible’s singular authority. This article shows that many new religious movements were not outliers in nineteenth-century Christian culture but were in fact products of that culture, albeit reactionary ones.