Many spiritual writers point to the mystical reality of the worship of Christ who remains both our High Priest and Victim and intercedes for us in heaven. Their spiritual treasury echoes the words of Revelation, “Worthy is the Lamb that was slain to receive power and riches, wisdom and strength, honor and glory and blessing.” (Rev. 5:12) The words of Revelation cause us to reflect further on the meaning of this vision for our authentic worship of God “on earth.” In offering himself to his Father in the sacrifice re-presented in the Mass, Christ offers his mystical body also, that is, the community of all those who belong to the Church on earth, in heaven or purgatory. Thus, Christ offers not only himself. He offers the Church on earth in communion with him, with the saints, and with the poor souls in purgatory. This offering in heaven is beyond time and place. We are, by Christ’s power, brought all together before the throne in heaven.
Full and active participation in the Mass requires our own freely chosen participation in this supernatural offering that Christ makes of his mystical body along with himself to the Father. Our desire to be united to Christ in his sacrifice is our response to the gift of the Mass as it unfolds around us in sight, in sound, in the smell of fire and incense, in the words proclaimed and heard, in the postures of each movement of the liturgy, and, above all, in our reception of his sacred Body and Blood in Holy Communion.
The Sacrifice of the Head and the Body of the Church
In the Eucharist the sacrifice of Christ becomes the sacrifice of the members of his body. The Catechism of the Catholic Church teaches that the mystical body of Christ, which is the Church, participates in the offering of Christ the Head. (1368) The Church unites herself to his intercession. “The lives of the faithful, their praise, sufferings, prayer, and work, are united with those of Christ and with his total offering, and so acquire a new value. Christ's sacrifice present on the altar makes it possible for all generations of Christians to be united with his offering.” (CCC 1368) To this offering of Christ, the Catechism says, are united also the members of the body already in the glory of heaven. The Church offers the Eucharistic sacrifice in union with and commemorating the Blessed Virgin Mary and all the saints. (1370) The sacrifice is offered also for those who have died in Christ but are not yet wholly purified, the souls in purgatory, that they may be able to enter into the light and peace of Christ. (1371)
As the Catechism goes on to say,
By grace, we can be united mystically to Christ in his offering. We begin with this fact: through baptism, we are grafted onto Christ, the root of all holiness. Through baptismal grace, as St Paul asserts, “I no longer live, but Christ lives in me” (Gal 2:20).