“To accomplish so great a work, Christ is always present in His Church, especially in her liturgical celebrations. He is present in the sacrifice of the Mass, not only in the person of His minister, ‘the same now offering, through the ministry of priests, who formerly offered himself on the cross,’ but especially under the Eucharistic species. By His power He is present in the sacraments, so that when a man baptizes it is really Christ Himself who baptizes. He is present in His word, since it is He Himself who speaks when the holy scriptures are read in the Church. He is present, lastly, when the Church prays and sings, for He promised: ‘Where two or three are gathered together in my name, there am I in the midst of them (Matt. 18:20).’”
“Rightly, then, the liturgy is considered as an exercise of the priestly office of Jesus Christ. In the liturgy the sanctification of the man is signified by signs perceptible to the senses, and is effected in a way which corresponds with each of these signs; in the liturgy the whole public worship is performed by the Mystical Body of Jesus Christ, that is, by the Head and His members.” (Sacrosanctum Concilium (Constitution on the Sacred Liturgy from the Second Vatican Council) 7).
“In the earthly liturgy we take part in a foretaste of that heavenly liturgy which is celebrated in the holy city of Jerusalem toward which we journey as pilgrims, where Christ is sitting at the right hand of God, a minister of the holies and of the true tabernacle; we sing a hymn to the Lord's glory with all the warriors of the heavenly army; venerating the memory of the saints, we hope for some part and fellowship with them; we eagerly await the Saviour, Our Lord Jesus Christ, until He, our life, shall appear and we too will appear with Him in glory” (Sacrosanctum Concilium (Constitution on the Sacred Liturgy from the Second Vatican Council) 8).
“The celebration of Mass [the Sacred Liturgy], as the action of Christ and the People of God arrayed hierarchically, is the center of the whole Christian life for the Church both universal and local, as well as for each of the faithful individually. In it is found the high point both of the action by which God sanctifies the world in Christ and of the worship that the human race offers to the Father, adoring him through Christ, the Son of God, in the Holy Spirit. In it, moreover, during the course of the year, the mysteries of redemption are recalled so as in some way to be made present. Furthermore, the other sacred actions and all the activities of the Christian life are bound up with it, flow from it, and are ordered to it” (General Instruction on the Roman Missal 16).
“In the liturgy of the New Covenant every liturgical action, especially the celebration of the Eucharist and the sacraments, is an encounter between Christ and the Church. The liturgical assembly derives its unity from the "communion of the Holy Spirit" who gathers the children of God into the one Body of Christ. This assembly transcends racial, cultural, social—indeed, all human affinities” (Catechism of the Catholic Church 1097).
Included in the liturgy of the New Covenant, “‘[the] public prayer of the Church,’” is “The mystery of Christ, his Incarnation and Passover, which we celebrate in the Eucharist especially at the Sunday assembly, permeates and transfigures the time of each day, through the celebration of the Liturgy of the Hours, ‘the divine office’” (Catechism of the Catholic Church 1174).