The addition of "one" before "God" "could serve to undermine the statement of the unique dignity of the Son within the Trinity", or "could be interpreted as saying that Jesus is 'one God,'" an explanatory note to the English and Welsh decree stated.
"Either or both of these interpretations is injurious to the faith of the Church."
Continuing, the note said that "one" "risks suggesting that Jesus became a god independent of the Blessed Trinity and is one god among many ... what we pray needs to express what the Church believes, requiring that, in liturgical formulae, we uphold the doctrine of the Blessed Trinity."
The Trinitarian doxology that concludes the collects "emphasises the divinity of Our Lord Jesus Christ, the Second Person of the Blessed Trinity, who as the Incarnate Son, intercedes on our behalf to the Father ... thus, the Son's role of priestly mediation is made clear."
The explanatory note says the phrase was adopted in the fourth century "as a means to combat the Arian heresy," which held that Jesus Christ became God, rather than having been God eternally.
Moreover, the note adds, "one" is not used in the translations of the conclusion in French, German, Italian, Spanish, or Portuguese: "The English translation has, therefore, diverged from those of other major language groups."
The English and Welsh bishops' explanatory note said that "since the addition of the word 'one'" could obscure prayer and thus belief, the Congregation for Divine Worship "has ruled it should no longer be used in the translation of these texts into English."
The USCCB has been approving new translations of components of the Liturgy of the Hours, a new translation of the Roman Missal having been adopted in 2011.
At its 2019 fall general assembly, the conference voted overwhelmingly to approve the ICEL grey book translation of the hymns of the Liturgy of the Hours.