From the essay “It’s about Faith in Our Future: Star Trek Fandom as Cultural Religion” by Michael Jindra:
Most Americans think of “religion” as a system of private, conscious, and articulated beliefs, usually expressed in churches and formal creeds, and set off from the other “spheres” of life such as work, politics, or leisure. This view of religion, however, stems from the specifically Western process of societal “differentiation,” in which institutional religion was given a specific function. After the medieval era, when religious practice was intimately connected to everyday life, the practice of Christianity became “abstracted,” or disconnected from everyday life. As a result, we now tend to regard “religion” as something connected to institutions such as churches and denominations. Alternatively, we view it as something personal and private, a psychological aid that is only peripherally connected to a person’s life.
This view of religion severely limits our understanding of it….
Religion and Popular Culture in America, ed. Bruce David Forbes and Jeffrey H. Mahan (Berkeley: University of California Press, 2000, rev. ed. 2005), p. 161.
Using a more expansive definition of religion, Jindra goes on to demonstrate how Star Trek fandom can be understood as a kind of humanist religion. He supports this in part by citing an interview with Rodenberry published in the March/April, 1991, issue of American Humanist, in which Rodenberry said he saw Star Trek as based on a humanist philosophy wherein human beings take control of their own destiny.