I am glad to have the opportunity to join the discussion here at the RLI. My name is Aaron Cummings and I am an interested lay person. Thanks much.
In most traditional liturgies which have survived to this day, the Agnus Dei is said immediately after Consecration of the element, and the declaration: “The Peace of the Lord be with you always.” In some churches, the minister goes so far as to say while elevating the host: “Behold the Lamb of God. Behold Him that taketh away the sins of the world.” The words of the Agnus Dei are:
“O Lamb of God which taketh away the sins of the world, have mercy upon us.
O Lamb of God which taketh away the sins of the world, have mercy upon us.
O Lamb of God which taketh away the sins of the world, grant us thy peace.”
These words are nice enough as it is. They are well-worth singing in the service, for our Lord is the Lamb of God who does take away the sins of the world. We should beg his mercy and peace.
What follows is merely a suggestion and I would welcome any feedback.
1) These words coming at this point in the service suggest that now Christ is here in a special way in the newly consecrated elements, here, that is, in such a way that we could pray to the elements.
2) If you quote John in pointing to the elements as Christ, then are you more pointedly asking the congregants to pray to the elements?
3) Would these words work better as a hymn of confession at the start of service? Consider that male lambs (rams in particular) were sacrificed as the trespass offering, the first of the sacrifices in the Levitical service. The Trespass was the sacrifice for the heavy, high-handed sins (Lev. 5:14-6:7). That Christ is our “lamb” specially identifies him specifically as the trespass offering, for when offering the other sacrifices (burnt, grain, peace, and sin), the sacrificing saint could offer goats, bulls, doves, pigeons and even bread. Christ certainly fulfills the other sacrifices, but John didn’t say, “Behold the goat of God”, or “Behold the bread of God”. He said, “Behold the Lamb of God,” highlighting the trespass sacrifice. The Agnus Dei seems to work very well as a hymn of confession rather than a hymn of joy at the Lord’s table. What about praying the Agnus and then the Kyrie as sister hymns of confession?