Today’s Catechism sections discuss the role of priests in the life of the Church. Supporting material comes from the Constitution, “Sacrosanctum Concilium”.

Two participations in the one priesthood of Christ

1546 Christ, high priest and unique mediator, has made of the Church "a kingdom, priests for his God and Father."20 The whole community of believers is, as such, priestly. The faithful exercise their baptismal priesthood through their participation, each according to his own vocation, in Christ's mission as priest, prophet, and king. Through the sacraments of Baptism and Confirmation the faithful are "consecrated to be . . . a holy priesthood."21

1547 The ministerial or hierarchical priesthood of bishops and priests, and the common priesthood of all the faithful participate, "each in its own proper way, in the one priesthood of Christ." While being "ordered one to another," they differ essentially.22 In what sense? While the common priesthood of the faithful is exercised by the unfolding of baptismal grace - a life of faith, hope, and charity, a life according to the Spirit - ,the ministerial priesthood is at the service of the common priesthood. It is directed at the unfolding of the baptismal grace of all Christians. The ministerial priesthood is a means by which Christ unceasingly builds up and leads his Church. For this reason it is transmitted by its own sacrament, the sacrament of Holy Orders.

In the person of Christ the Head . . .

1548 In the ecclesial service of the ordained minister, it is Christ himself who is present to his Church as Head of his Body, Shepherd of his flock, high priest of the redemptive sacrifice, Teacher of Truth. This is what the Church means by saying that the priest, by virtue of the sacrament of Holy Orders, acts in persona Christi Capitis:23

It is the same priest, Christ Jesus, whose sacred person his minister truly represents. Now the minister, by reason of the sacerdotal consecration which he has received, is truly made like to the high priest and possesses the authority to act in the power and place of the person of Christ himself (virtute ac persona ipsius Christi).24
Christ is the source of all priesthood: the priest of the old law was a figure of Christ, and the priest of the new law acts in the person of Christ.25

1549 Through the ordained ministry, especially that of bishops and priests, the presence of Christ as head of the Church is made visible in the midst of the community of believers.26 In the beautiful expression of St. Ignatius of Antioch, the bishop is typos tou Patros: he is like the living image of God the Father.27

1550 This presence of Christ in the minister is not to be understood as if the latter were preserved from all human weaknesses, the spirit of domination, error, even sin. The power of the Holy Spirit does not guarantee all acts of ministers in the same way. While this guarantee extends to the sacraments, so that even the minister's sin cannot impede the fruit of grace, in many other acts the minister leaves human traces that are not always signs of fidelity to the Gospel and consequently can harm the apostolic fruitfulness of the Church.

1551 This priesthood is ministerial. "That office . . . which the Lord committed to the pastors of his people, is in the strict sense of the term a service."28 It is entirely related to Christ and to men. It depends entirely on Christ and on his unique priesthood; it has been instituted for the good of men and the communion of the Church. The sacrament of Holy Orders communicates a "sacred power" which is none other than that of Christ. The exercise of this authority must therefore be measured against the model of Christ, who by love made himself the least and the servant of all.29 "The Lord said clearly that concern for his flock was proof of love for him."30

. . . "in the name of the whole Church"

1552 The ministerial priesthood has the task not only of representing Christ - Head of the Church - before the assembly of the faithful, but also of acting in the name of the whole Church when presenting to God the prayer of the Church, and above all when offering the Eucharistic sacrifice.31

1553 "In the name of the whole Church" does not mean that priests are the delegates of the community. The prayer and offering of the Church are inseparable from the prayer and offering of Christ, her head; it is always the case that Christ worships in and through his Church. The whole Church, the Body of Christ, prays and offers herself "through him, with him, in him," in the unity of the Holy Spirit, to God the Father. The whole Body, caput et membra, prays and offers itself, and therefore those who in the Body are especially his ministers are called ministers not only of Christ, but also of the Church. It is because the ministerial priesthood represents Christ that it can represent the Church.

The Constitution, “Sacrosanctum Concilium” (33) discusses the role of the priest in the liturgy.

33. Although the sacred liturgy is above all things the worship of the divine Majesty, it likewise contains much instruction for the faithful [34]. For in the liturgy God speaks to His people and Christ is still proclaiming His gospel. And the people reply to God both by song and prayer.

Moreover, the prayers addressed to God by the priest who presides over the assembly in the person of Christ are said in the name of the entire holy people and of all present. And the visible signs used by the liturgy to signify invisible divine things have been chosen by Christ or the Church. Thus not only when things are read "which were written for our instruction" (Rom. 15:4), but also when the Church prays or sings or acts, the faith of those taking part is nourished and their minds are raised to God, so that they may offer Him their rational service and more abundantly receive His grace.

Footnotes

20 ⇒ Rev 1:6; cf. ⇒ Rev 5:9-10; ⇒ 1 Pet 2:5, 9.
21 LG 10 # 1.
22 LG 10 # 2.
23 Cf. LG 10; 28; SC 33; CD 11; PO 2; 6.
24 Pius XII, encyclical, Mediator Dei: AAS, 39 (1947) 548.
25 St. Thomas Aquinas, STh III, 22, 4c.
26 Cf. LG 21.
27 St. Ignatius of Antioch, Ad Trall. 3, 1: SCh 10, 96; cf. Ad Magn. 6, 1: SCh 10, 82-84.
28 LG 24.
29 Cf. ⇒ Mk 10 43-45; ⇒ 1 Pet 5:3.
30 St. John Chrysostom, De sac. 2, 4: PG 48, 636; cf. ⇒ Jn 21:15-17.
31 Cf. SC 33N; LG 10.