American Fanatics: Religion, Rebellion, and Empire in the Nineteenth Century

My current book project, American Fanatics, is being published Spring 2026 as part of New York University Press’s North American Religions Book Series.

In 1822 Thomas Jefferson wrote that “the atmosphere of our country is unquestionably charged with a threatening cloud of fanaticism.” Jefferson’s forecast was accurate. The United States in the 1800s was full of radical theologies, messiahs, utopian dreams, passionate exhortations, and sacred violence. Whether these lightning storms constituted a religious energy vital to the national and imperial spirit (what Jefferson called the “empire of liberty”) or a threatening storm that threatened human reason and social order was an open question.

American Fanatics is the first book to provide a history of fanaticism in the United States. It examines fanaticism as an “overflowing signifier,” meaning that research on fanaticism requires care because the term is inherently political, full of biases, and assumptions. It traces the rise of the concept of fanaticism through distinct conflicts over evangelical revivals, abolition, sentimental literature, psychiatry, and colonial anthropology. The book argues that American uses of the term shifted from the 1800s to the early 1900s. White American Protestants, shedding past accusations of fanatical rituals, began to use fanaticism as a religious and a racial concept that signified essential civilizational capacities. Clergy, secular intellectuals, and government agents increasingly distinguished enthusiasm, as a spiritual and national good, from fanaticism, as a global problem that the United States could solve through Christian mission and power.