We sometimes recite or sing the Gloria every Sunday at Mass, Solemnities, and Feasts except in Advent and Lent. What is the Church’s reason?

Advent is a great season of preparation for a greater mystery: the Nativity of Jesus at Christmas. The omission of Gloria, a song that recalls the Lord’s first coming, gives us pause during this season to think of what is missing. In reflecting upon what is missing, Advent, which is a penitential season of the Church, calls us to the same conversion that St. John the Baptist called the Jews as they awaited the arrival of the Messiah. Even though the Church sings "Alleluia" during Advent, because the Gloria is a prayer or song of joy, it is suppressed during Advent and is not heard until the vigil Mass on Christmas Eve. Therefore, since Gloria is the Mother of all Carols, we don’t sing the mother-of-all carols, the song of the angels, until the appropriate time (Chinaka, 2016). It also predisposes us to pray for His Second Coming; ultimately, it prepares us to joyfully sing the Gloria on Christmas when we celebrate the Lord’s coming. However, when there is a Solemnity at Advent (for example, the Immaculate Conception), the Gloria can be said or chanted. (Dubruiel, 2007)

Lent is also a penitential season. This means that it is a time for us to be honest about what needs to change in our lives as well as how we need to grow closer to God. It begins with the imposition of ashes on our foreheads on Ash Wednesday when we are reminded of Adams and Eve’s fault: "Remember you are dust, and dust you will return". We are called to meditate on what our lives would be like if Christ did not come to save us; hence, the Church refrains from the Gloria during Lent. It also allows us to wallow a bit in our sins, but only to more fully experience what God has done for us in sending His Son, who moves toward Jerusalem to suffer and die for our sins. Fittingly, at the beginning of the Easter Triduum (literally the "three-day festival of Easter") on Holy Thursday, bells will ring joyfully as we sing the Gloria at the end of our long fast. (Dubruiel, 2007)