The Gospel For The Lord's Baptism
If we are open to the fact that the gospels are actual liturgy (as well as lectionary and catechism) we can see a piece of the church's most primitive liturgy in vss 16 and 17 of Sunday's gospel.
Whenever something can easily be divided into versicle and response it is a strong indicator in my mind that that is exactly what it was / is. It is easy to imagine in the primitive church that mass conversions and baptisms were occurring every Sunday, and that this was part of their liturgy and baptismal rite. That it was a doxological and catechetical recitation of the blessed facts and acts of our salvation; by which the newly baptized became God's sons in whom he is well pleased. And what was true then for them, is also true for us now. God be praised.
(My translation of Luke 3:15-22)
15 Because the people were in a state of expectation, and everyone wondering in their hearts concerning John, whether he might be the Christ; 16 John answered them all with this saying,
V: "I baptize you with water,
R: but One who is mightier than I is coming
V: the strap of whose sandal I am not fit to untie.
R: He will baptize you with the Holy Spirit and Fire.
V: His winnowing fork is in his hand!
R: and he will thoroughly clean is threshing floor.
V: He will gather the wheat into his barn,
R: but the chaff he will burn with fire unquenchable."
18 And with many other exhortations he preached the gospel to the people.
19 But Herod the Tetrarch, who had been reproved by him because of Herodias his brother Philipp's wife, and for all the evil things he had done, 20 added this to all the rest: he locked up John in prison.
21 Now when all the people had been baptized, and Jesus also had been baptized and was praying the skies opened 22 and the Holy Spirit descended upon him, bodily, in the form of a dove; and a voice came from Heaven saying,
"You are my beloved Son with you I am well pleased."