Agnus Dei

Lamb of God (Greek: Ἀμνὸς τοῦ Θεοῦ, Amnos tou Theou; Latin: Agnus Dei) is a title for Jesus that appears in the Gospel of John. It appears at , where John the Baptist sees Jesus and exclaims, "Behold the Lamb of God who takes away the sin of the world."

Christian doctrine holds that divine Jesus chose to suffer crucifixion at Calvary as a sign of his full obedience to the will of his divine Father, as an "agent and servant of God". In Christian theology the Lamb of God is viewed as foundational and integral to the message of Christianity.

A lion-like lamb that rises to deliver victory after being slain appears several times in the Book of Revelation. It is also referred to in Pauline writings, suggests that Saint Paul intends to refer to the death of Jesus, who is the Paschal Lamb, using the theme found in Johannine writings. The lamb metaphor is also in line with Psalm 23, which depicts God as a shepherd leading his flock (mankind).

The Lamb of God title is widely used in Christian prayers, and the Agnus Dei is used as a standard part of the Catholic Mass, as well as the classical Western Liturgies of the Anglican and Lutheran Churches. It also is used in liturgy and as a form of contemplative prayer. The Agnus Dei also forms a part of the musical setting for the Mass.

...
Wikipedia