This essay addresses the question of how the idea of liberalism and antireligious sentiment became associated during the Gilded Age. The subject of this essay—the New York Liberal Club, a debate and lecture group in New York City (1869–1877)—sheds light on the process in which liberalism, as an idea, outgrew its religious origins in early nineteenth-century America and more than ever became linked with antireligious sentiment. In the case of the New York Liberal Club, this development owed to the club's connection to social science and members' participation in the contentious debate over science and religion during the 1870s. In addition, it partly owed to club members' conception of liberalism as tolerance, open-mindedness, and a commitment to the free exchange of ideas. Because of this conception of liberalism, many club members saw liberalism and social science as a common cause, since both reflected a dedication to improving the world through free inquiry. Ultimately, these conceptions, as well as discourse at the club, led many observers in the public to incorrectly view all Liberal Club members (and liberalism itself) as in opposition to faith and religious belief.