We do not sing at Mass; we sang Mass. Therefore, not just anything can be sung during a Eucharistic Celebration.
The texts that appear in the Roman Missal, whether they are from the ordinary of the Mass (Kyrie, Gloria, Holy, Our Father, Lamb of God) or from the proper of the day (collect prayers, on offerings, post communion, preface), can be sung with different tones or melodies. You just have to respect the text and not change it. For example, at the beginning of the Rite of Communion it is not possible to sing “Our Father, You who are in those who love the truth…” because it is the time to pray the Lord’s Prayer; we cannot change the words with which Jesus himself taught us to pray for others.
There are other moments when one can sing, but in which there is no text given by the Roman Missal. This is the case of entrance, the preparation of the gifts and communion. In these cases, the General Instruction of the Roman Missal provides for the singing of the antiphon provided for each celebration by the Roman Gradual or the Simple Gradual (nn. 48, 74, 87).
The Roman Gradual, the latest version of which is from 1974, includes the texts set to music for these parts of the Mass. The Second Vatican Council asked that “an edition be prepared containing simpler modes, for the use of the minor churches” (Sacrosanctum Concilium 117). That is why a simplified version called ” Simple Gradual” was published.
However, the General Instruction of the Roman Missal permits that, instead of the antiphons of the Gradual, in the entrance, in the preparation of the gifts, and in communion, other chants be used, but it establishes that the texts of these chants must be approved by the Conference of Bishops (GIRM 48, 74, 87, 390). That is to say, not just any musical composition that is made will do; It must be approved by the Episcopal Conference to ensure that its text is in accordance with the faith.
For example, not singing the song “Jesus the Friend” at communion. In the text it is said “in every mass you repeat your sacrifice”. However, in the Letter to the Hebrews (Hebrews 7:27) it is said that Jesus offered his sacrifice once and for all; that is, in the Mass the sacrifice is not repeated as the song says; it would have to be said that sacrifice is renewed (CCC 1364, Lumen Gentium 3)
The texts of the graduals are, fundamentally, verses of Sacred Scripture, which gives a clue to the songs that have to be composed for these moments: they must have a biblical basis.
In addition to being approved by the Conference of Bishops, care must be taken that the songs are appropriate to the nature of the sacred action, to the liturgical day or season (GIRM 48). It is not relevant, for example, to sing “Forgive us, your people” at Christmas; or “Soon and Very Soon” on Easter Sunday.
When choosing music for the mass, we are to select songs that have been composed solely for the liturgy, let us promote the songs adequate with the liturgical season, so that music may be a unity with the liturgy, to be perceived by our senses and thus transform our hearts to be ready to listen to the voice of God.
Papal Liturgy, “¿Qué se puede cantar en Misa?” LiturgiaPapal.org, Accesed 6 August 2024, https://liturgiapapal.org/index.php/manual-de-liturgia/m%C3%BAsica-lit%C3%BArgica/780-%C2%BFqu%C3%A9-se-puede-cantar-en-misa.html