Q: I understand that Pope Sergius (c. 700) introduced the Agnus Dei, of Syriac origin, into the Roman liturgy. My understanding is that, even then, the phrase was “peccata mundi” – “sins [plural] of the world”. The same is found in the 1962 as well as the current missal (echoing the Gloria): sins (peccata) of the world.
I’ve looked at the original Greek (uses the singular, “sin of the world”) as well as the vulgate (peccatum) and neo-vulgate (peccatum). John Meyer states that, in John’s gospel, “sin” is a dogmatic (not a moral) category – the “sin of the world” is unbelief.
So why is the liturgical use plural while the scriptural originating text is singular?
Given how much ink was spilled on arguing whether “many” / “the many” / “ the multitude” / or “all” should be used in the liturgy (originating text Matt 26:28), it seems inconsistent to only “loosly” connect to the Johannine text but very literally to the Matthean.
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A: In both cases (“sins” and “many”), the English translation of the Missal gives you what appears in the Latin edition of the missal. I answered a related question here: https://paulturner.org/supper-of-the-lamb/
The liturgical texts are not readings from the bible. That’s what the readings are for. The liturgical texts are inspired by the bible. “Shepherd Me, O God,” and “On Eagle’s Wings” are paraphrases. No one expects them to quote the bible exactly.
It would be guesswork to answer why the origins of the Lamb of God put “sins” in the plural. Perhaps at the time people thought it personalized the biblical testimony in a way that helped them prepare for communion. Perhaps other generations liked the long-lost tunes. Somehow the poetic words got handed down. It’s a wonder we have such texts at all.