Lutheran Church—Missouri Synod in the context of "Evangelical Lutheran Church in America"

Formal principle and material principle are two categories in Christian theology to identify and distinguish the authoritative source of theology (formal principle) from the theology itself, especially the central doctrine of that theology (material principle), of a religion, religious movement, tradition, body, denomination, or organization. A formal principle tends to be texts or revered leaders of the religion; a material principle is its central teaching. Paul Tillich believes the identification and application of this pair of categories in theological thinking to have originated in the 19th century.

As early as 1845 the Protestant theologian and historian Philip Schaff discussed them in his The Principle of Protestantism. They were utilized by the Lutheran scholar F. E. Mayer in his The Religious Bodies of America in order to facilitate a comparative study of the faith and practice of Christian denominations in the United States. This is also treated in a theological pamphlet entitled Gospel and Scripture by the Commission on Theology and Church Relations of the Lutheran Church—Missouri Synod.

The Lutheran Book of Worship (LBW) is a worship book and hymnal published in 1978 and was authorized for use by several Lutheran denominations in North America, including predecessors of the Evangelical Lutheran Church in America and Evangelical Lutheran Church in Canada. The Lutheran Church—Missouri Synod was initially involved in the hymnal's development but officially withdrew.

Additional hymns and service music are contained in the companions Hymnal Supplement 1991 and With One Voice (WOV). A successor was published in 2006 titled Evangelical Lutheran Worship, although Lutheran Book of Worship remains in use by some congregations.