Latin for “Lamb of God,” this is a prayer to Christ that, as Redeemer of the world, He listen to our prayers, give us whatever we need for faith and life, and keep us in a peaceful relationship with Him. It occurs at least twice in the historic liturgical service of the Western Church.
It is first sung in the Gloria in Excelsis, with the additional address “Son of the Father” inserted after “O Lamb of God.” In addition, since before the 7th century it has been sung after the consecration of the elements in the Lord’s Supper as a prayer to Christ Himself being present in His Body and Blood in His Sacrament on the altar.
During the 10th and 11th centuries the words “grant us Thy peace” replaced the third “have mercy upon us,” due to the many terrible calamities the church was then suffering.
The Agnus Dei was included in both Luther’s Latin and German services, and has been a part of the Lutheran liturgy in both Europe and America since the time of the Reformation.
Because of their rejection of the Real Presence of Christ in His Supper through the sacramental union, the English Reformers omitted the Agnus Dei from the Communion rite in the 1552 and later editions of the Book of Common Prayer. It was restored in the 1929 Scottish Liturgy, but not in the 1928 American Book.