CCC 1158 The harmony of signs (song, music, words, and actions) is all the more expressive and fruitful when expressed in the cultural richness of the People of God who celebrate.¹ Hence “religious singing by the faithful is to be intelligently fostered so that in devotions and sacred exercises as well as in liturgical services,” in conformity with the Church’s norms, “the voices of the faithful may be heard.” But “the texts intended to be sung must always be in conformity with Catholic doctrine. Indeed they should be drawn chiefly from the Sacred Scripture and from liturgical sources.”²

1 Cf. SC 119.
2 SC 118; 121.