‘Religion’ is generally understood as a body of values, beliefs, and practices concerning the cosmos, humanity, and God or gods, commonly involving official doctrines, rites, rituals, and a moral code to direct human behaviour. ‘Curriculum’ refers to the aggregate courses of study in an educational institution, or a set of courses in a specialised field within an institution. ‘Religious curriculum’ is, therefore, curriculum pertaining to religious beliefs, doctrine, practices, and values. For much of American history, religious curriculum played an integral role in education. For Native Americans, education was mostly informal, conceptualised and delivered holistically so that no disjuncture occurred between the material and spiritual worlds. For most African Americans, until the Civil War, formal education occurred predominantly in church and thus the curriculum was significantly religious in nature.

During colonial America (1607–1783), Bible-centric religious curriculum permeated education in private, public, and home schools. Influenced by Protestantism, many colonists believed the noblest aim of education was to lead individuals to salvation and subsequent cultivation of Christian virtue. After the Revolutionary War, Protestant-centric values and beliefs continued to infuse curriculum through the end of the nineteenth century, aided by the McGuffey Readers, which were (other than the Bible) the best-selling books of that century. However, after the Civil War, the grip that broad, non-sectarian Protestantism had held over curriculum began to loosen due to increasingly diverse immigrant populations (primarily Catholics and Jews, who resisted Protestant hegemony in public education), rapid industrial and technological advances (which required greater emphasis on science), the secularisation of higher education, and growing efforts to centralise and consolidate educational systems. By the beginning of the twentieth century, Protestantism’s hegemony in American public education had weakened as America had become more religiously diverse and pluralistic.

In the mid-twentieth century, the Supreme Court applied the Establishment Clause, ‘Congress shall make no law respecting an establishment of religion’, and the Free Exercise Clause, ‘[Congress shall make no law] prohibiting the free exercise [of religion]’, by way of the Fourteenth Amendment to the states and to local school districts. Their decisions resulted in the removal of school-sponsored, devotional religious curriculum from US education. Conservative Christians reacted in the ensuing decades, petitioning (usually unsuccessfully) for the reimplementation of biblical content and perspectives in curriculum. Beginning in the 1990s, two organisations, the National Council for Bible Curriculum in Public Schools and the Bible Literacy Project, began providing their own curriculum to state and local school boards for incorporating the Bible in an academic, non-devotional manner that does not violate the Establishment or Free Exercise Clauses. Contemporary public schools have a mixture of world religions courses, elective Bible courses, and released time programmes, in which public school students are permitted to leave campus for devotional religious education. Although there is broad scholarly consensus regarding the advantages of including religious curriculum in public schools, constitutional issues, teacher training, and methodologies for doing this are highly contested.