Agnus Dei is the Latin name under which the “Lamb of God” is honoured within Christian liturgies descending from the historic Latin liturgical tradition, including those of Roman Catholicism, Lutheranism, and Anglicanism. It is the name given to a specific prayer that occurs in these liturgies, and is the name given to the music pieces that accompany the text of this prayer. The use of the title “Lamb of God” in liturgy is based on John 1:29, in which St. John the Baptist, upon seeing Jesus, proclaims “Behold, the Lamb of God, who takes away the sin of the world!”
The Syrian custom of a chant addressed to the Lamb of God was introduced into the Roman Rite Mass by Pope Sergius I (687–701) in the context of his rejection of the Council of Trullo of 692 (which was well received in the Byzantine East), whose canons had forbidden the iconographic depiction of Christ as a lamb instead of a man.
| Agnus Dei, qui tollis peccata mundi, miserere nobis. Agnus Dei, qui tollis peccata mundi, miserere nobis. Agnus Dei, qui tollis peccata mundi, dona nobis pacem. | Lamb of God, who takes away the sins of the world, have mercy on us. Lamb of God, who takes away the sins of the world, have mercy on us. Lamb of God, who takes away the sins of the world, grant us peace. |
| —Latin | —English translation |
The verse used in the first and second invocations may be repeated as many times as necessary whilst the celebrant prepares the host and wine for communion. Virtually every mass setting includes an Agnus Dei. The priest uses the phrase “Lamb of God” again, later in the Mass. While displaying the Eucharistic species to the people before giving them Holy Communion, he says: “Ecce Agnus Dei, ecce qui tollit peccata mundi. Beati qui ad cenam Agni vocati sunt.” (“Behold the Lamb of God, behold Him who takes away the sins of the world. Blessed are those called to the supper of the Lamb.”)
A popular worship song among Evangelical Protestants tradition is a rendition of the traditional Agnus Dei by Michael W. Smith. Based on a paraphrase of Revelation 5, the words are:
Alleluia Alleluia
For our Lord God Almighty reigns
Alleluia Alleluia
For our Lord God Almighty reigns
Alleluia Holy
Holy
Are You Lord God Almighty
Worthy is the Lamb
Worthy is the Lamb
You are Holy
(Last stanza repeats 3 times)
A Ukranian translation was sung in 2015 in Lviv, Ukraine, during the War in the Donbass at an event organized by Franklin Graham. The song was notably sung again on Easter 2022 in Lviv by a choir of Ukrainian refugees fleeing the Russo-Ukrainian War.
