Answer
Agnus Dei is a Latin term. Translated into English, it is “Lamb of God.”
The biblical basis for this imagery is found in John 1:29: “John saw Jesus coming toward him and said, ‘Look, the Lamb of God, who takes away the sin of the world!’” and in Revelation 5:9–14, where the Lamb who has been slain is worshiped: “‘You are worthy to take the scroll and to open its seals, because you were slain, and with your blood you purchased for God persons from every tribe and language and people and nation. You have made them to be a kingdom and priests to serve our God, and they will reign on the earth.’ Then I looked and heard the voice of many angels, numbering thousands upon thousands, and ten thousand times ten thousand. They encircled the throne and the living creatures and the elders. In a loud voice they were saying: ‘Worthy is the Lamb, who was slain, to receive power and wealth and wisdom and strength and honor and glory and praise!’ Then I heard every creature in heaven and on earth and under the earth and on the sea, and all that is in them, saying: ‘To him who sits on the throne and to the Lamb be praise and honor and glory and power, for ever and ever!’ The four living creatures said, ‘Amen,’ and the elders fell down and worshiped.”
The imagery in Revelation 5 captures both the sacrifice and the victory of Christ, the Lamb. He is not only the slain Agnus Dei but also the victorious, risen, conquering Agnus Dei.
The term Agnus Dei has become semi-technical in church history and liturgy and can refer to two things:
1. A figure of a lamb with a halo and bearing a cross or banner. This symbol for Christ is often found in church artwork and stained glass windows.
2. A prayer to Christ, which is part of the Roman Catholic liturgy.
• In Latin: “Agnus Dei, qui tolis peccata mundi, miserere nobis. Agnus Dei, qui tolis peccata mundi, dona nobis pacem.”
• In English: “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.”
Singer and songwriter Michael W. Smith has written and arranged a modern hymn that bears the name Agnus Dei. The song, which contains the refrain, “Worthy is the Lamb,” has become quite popular in churches.
While Catholics and Evangelicals agree that Jesus is the Lamb of God who takes away the sins of the world, there is a difference in application that is worth noting:
In Roman Catholic theology, the Agnus Dei is a prayer for mercy as one would plead for leniency before a judge, not knowing the final outcome. For the faithful Catholic, this prayer is part of the cycle of sin, confession, and penance by which grace is gradually infused so that, over time, the sinner becomes righteous enough so that God may be justified in saving him or her.
For the Evangelical who has trusted in Christ for salvation, the Agnus Dei prayer as it is worded in the liturgy would take on a different meaning. The Evangelical knows that he or she has already been shown mercy and is at peace with God though faith in Christ. So, for him, this prayer would take on a tone of thanksgiving for the blessings already received. Perhaps the following wording would reflect better theology: “Lamb of God, who takes away the sins of the world, thank you for your mercy on us. Lamb of God, who takes away the sins of the world, thank you for your peace.”