6 Just as Christ was sent by the Father, so also He sent the apostles, filled with the Holy Spirit. This He did that, by preaching the gospel to every creature , they might proclaim that the Son of God, by His death and resurrection, had freed us from the power of Satan and from death, and brought us into the kingdom of His Father. His purpose also was that they might accomplish the work of salvation which they had proclaimed, by means of sacrifice and sacraments, around which the entire liturgical life revolves. Thus by baptism men are plunged into the paschal mystery of Christ: they die with Him, are buried with Him, and rise with Him ; they receive the spirit of adoption as sons "in which we cry: Abba, Father" ( Rom. 8 :15), and thus become true adorers whom the Father seeks . In like manner, as often as they eat the supper of the Lord they proclaim the death of the Lord until He comes . For that reason, on the very day of Pentecost, when the Church appeared before the world, "those who received the word" of Peter "were baptized." And "they continued steadfastly in the teaching of the apostles and in the communion of the breaking of bread and in prayers . . . praising God and being in favor with all the people" (Acts 2:41-47). From that time onwards the Church has never failed to come together to celebrate the paschal mystery: reading those things "which were in all the scriptures concerning him" (Luke 24:27), celebrating the eucharist in which "the victory and triumph of his death are again made present" , and at the same time giving thanks "to God for his unspeakable gift" (2 Cor. 9:15) in Christ Jesus, "in praise of his glory" (Eph. 1:12), through the power of the Holy Spirit.
Source: Sacrosanctum Concilium (Vatican.va)