One of the creators of modern American theological liberalism, Sophia Lyon Fahs was also the progenitor of American Unitarian religious education as a modern theological science of human emotions.

Born in 1876 to Presbyterian missionary parents in China, she embraced progressive educational principles when she was a graduate student at Columbia University's Teachers College, and later, as a divinity student at Union Theological School in New York. Following graduation, she joined Union's faculty in 1927. Fahs came of age as a major new force in liberal religious education at a time when young, liberal parents and disenchanted orthodox parents increasingly sought out new models of religious education for their children. Fahs preached and stoked emotional enthusiasm. She was, in this way, deeply influenced by John Dewey and his interpreters at Columbia University and Teachers College. She also actively created and shaped the progressive Sunday School at Riverside Church in New York. She had learned from John Dewey that teaching, as he put it, "is an art [and that] the teacher's own claim to rank as an artist is measured by [the teacher's] ability to foster the attitude of the artist in those who study with him [or her], whether they be youth or little children." Teachers, Dewey insisted, must "succeed in arousing enthusiasm, in communicating large ideas, in evoking energy... the final test [of the teaching being] whether the stimulus thus given to wide aims succeeds in transforming itself into power, that is to say, into the attention to detail that ensures mastery over means of execution. If not, the zeal flags, the interest dies out, the ideal becomes a clouded memory."

For more than 80 years as a professional educator, practical theologian, and author, Fahs strove to create a theology that restored human emotions and human experience to their rightful place as foundational building blocks for an enlightened liberal faith.

Biographer Edith Hunter notes that by the time she was 90, in 1966, Fahs' life had "touched four distinct theological generations of American Protestantism:" (1) the period from 1880 to 1905 of missionary enthusiasm with its goal of "the evangelization of the world in [the present] generation;" (2) the Social Gospel Movement period from 1905 to 1930 which "sought to transform an unjust social order into a just one through the application of the ethics of the historical Jesus;" (3) the rise of a new theological orthodoxy between 1930 and 1955 spearheaded by liberal theologians like Reinhold Niebuhr and Paul Tillich whose idealism, sundered by the Great Depression and World War II, turned into a new realism that espoused social justice ethics linked to a traditional, conservative assessment of the fallen state of human nature through sin; and finally (4) the rise of the Radical theologians, the New Atheists, and the Death-of-God theologians who rejected the notion of a personal God who benevolently intervenes in human affairs. Fahs was "a product, an observer, a participant, and to some extent a creator" (or more precisely a co-creator with other stellar figures) of this modern history of American Protestantism.

Fahs devoted her life to the big questions rather than to the big answers. As she put it:

In the great religions, especially those of the Western world, the accent has been upon beliefs and convictions, rather than upon questioning. In fact the distinguishing marks between the different religious sects have been, for the most part, the differences in their beliefs. Although beliefs are important we need to remind ourselves that they are the fruits of experience, and that in the natural world each new life begins with its own seed. As parents of children and as educators, we need to practice looking beneath the convictions to find the earlier experiences that awakened the questions which in turn called forth the answers given as convictions.

Fahs was Children's Editor for the Unitarian New Beacon Series from 1937, at age 61, until her retirement 14 years later in 1951. As editor, author, or co-author of more than a dozen books, she "addressed children directly using vivid stories from around the world." As one of her biographers observes, Fahs drew on "anthropological and psychological research... dedicated to one goal." Fahs summarized this goal: "We wish children to come to know God directly through original approaches of their own to the universe."

Although contemporary examination of Fahs' stories reveals that she oversimplified complex histories and peoples too readily in order to make them into children's fables and sometimes reduced complex lives to racial caricature, her work was ground-breaking in its time. Fahs' motto as a theologian, philosopher, and educator was: Emotional experience first. As she wrote in Worshipping Together with Questioning Minds:

Neither our classrooms nor our services of worship can profitably be turned in to debating societies. Neither will a silent evasion of all the issues encourage serious original thoughtfulness. The varied ideas that have been gathered up in to this three-letter word God are too pivotal in our study of religious history to be evaded. Thoughts of God are still too dominant in our Western society and too intimately [influential of] our common emotional life to be disregarded.

In what spirit then and by what techniques can we initiate and guide discussion of God among us?

Fahs devoted her life to discovering the questions that led to answers that included God-talk.

Fahs joined a Unitarian Church in 1945, and was ordained in 1959, at age 82, in what is now the Cedar Lane Unitarian Universalist Church in Bethesda, Maryland, as a Unitarian minister.