Catechism of the Catholic Church
1581 This sacrament configures the recipient to Christ by a special grace of the Holy Spirit, so that he may serve as Christ's instrument for his Church. By ordination one is enabled to act as a representative of Christ, Head of the Church, in his triple office of priest, prophet, and king.
1582 As in the case of Baptism and Confirmation this share in Christ's office is granted once for all. The sacrament of Holy Orders, like the other two, confers an indelible spiritual character and cannot be repeated or conferred temporarily. 74
1583 It is true that someone validly ordained can, for grave reasons, be discharged from the obligations and functions linked to ordination, or can be forbidden to exercise them; but he cannot become a layman again in the strict sense, 75 because the character imprinted by ordination is for ever. The vocation and mission received on the day of his ordination mark him permanently.
1584 Since it is ultimately Christ who acts and effects salvation through the ordained minister, the unworthiness of the latter does not prevent Christ from acting. 76 St. Augustine states this forcefully:
As for the proud minister, he is to be ranked with the devil. Christ's gift is not thereby profaned: what flows through him keeps its purity, and what passes through him remains dear and reaches the fertile earth.... The spiritual power of the sacrament is indeed comparable to light: those to be enlightened receive it in its purity, and if it should pass through defiled beings, it is not itself defiled. 77
1585 The grace of the Holy Spirit proper to this sacrament is configuration to Christ as Priest, Teacher, and Pastor, of whom the ordained is made a minister.
1586 For the bishop, this is first of all a grace of strength ("the governing spirit": Prayer of Episcopal Consecration in the Latin rite): 78 the grace to guide and defend his Church with strength and prudence as a father and pastor, with gratuitous love for all and a preferential love for the poor, the sick, and the needy. This grace impels him to proclaim the Gospel to all, to be the model for his flock, to go before it on the way of sanctification by identifying himself in the Eucharist with Christ the priest and victim, not fearing to give his life for his sheep:
Father, you know all hearts.
You have chosen your servant for the office of bishop.
May he be a shepherd to your holy flock,
and a high priest blameless in your sight,
ministering to you night and day;
may he always gain the blessing of your favor
and offer the gifts of your holy Church.
Through the Spirit who gives the grace of high priesthood
grant him the power
to forgive sins as you have commanded,
to assign ministries as you have decreed,
and to loose from every bond by the authority which you
gave to your apostles.
May he be pleasing to you by his gentleness and purity of heart,
presenting a fragrant offering to you,
through Jesus Christ, your Son.... 79
1587 The spiritual gift conferred by presbyteral ordination is expressed by this prayer of the Byzantine Rite. The bishop, while laying on his hand, says among other things:
Lord, fill with the gift of the Holy Spirit
him whom you have deigned to raise to the rank of the priesthood,
that he may be worthy to stand without reproach before your altar,
to proclaim the Gospel of your kingdom,
to fulfill the ministry of your word of truth,
to offer you spiritual gifts and sacrifices,
to renew your people by the bath of rebirth;
so that he may go out to meet
our great God and Savior Jesus Christ, your only Son,
on the day of his second coming,
and may receive from your vast goodness
the recompense for a faithful administration of his order. 80
1588 With regard to deacons, "strengthened by sacramental grace they are dedicated to the People of God, in conjunction with the bishop and his body of priests, in the service (diakonia) of the liturgy, of the Gospel, and of works of charity." 81
1589 Before the grandeur of the priestly grace and office, the holy doctors felt an urgent call to conversion in order to conform their whole lives to him whose sacrament had made them ministers. Thus St. Gregory of Nazianzus, as a very young priest, exclaimed:
We must begin by purifying ourselves before purifying others; we must be instructed to be able to instruct, become light to illuminate, draw close to God to bring him close to others, be sanctified to sanctify, lead by the hand and counsel prudently. I know whose ministers we are, where we find ourselves and to where we strive. I know God's greatness and man's weakness, but also his potential. [Who then is the priest? He is] the defender of truth, who stands with angels, gives glory with archangels, causes sacrifices to rise to the altar on high, shares Christ's priesthood, refashions creation, restores it in God's image, recreates it for the world on high and, even greater, is divinized and divinizes. 82
And the holy Cure of Ars: "The priest continues the work of redemption on earth.... If we really understood the priest on earth, we would die not of fright but of love.... The Priesthood is the love of the heart of Jesus." 83
1590 St. Paul said to his disciple Timothy: "I remind you to rekindle the gift of God that is within you through the laying on of my hands" (2 Tim 1:6), and "If any one aspires to the office of bishop, he desires a noble task." (1 Tim 3:1) To Titus he said: "This is why I left you in Crete, that you amend what was defective, and appoint presbyters in every town, as I directed you" (Titus 1:5).
1591 The whole Church is a priestly people. Through Baptism all the faithful share in the priesthood of Christ. This participation is called the "common priesthood of the faithful." Based on this common priesthood and ordered to its service, there exists another participation in the mission of Christ: the ministry conferred by the sacrament of Holy Orders, where the task is to serve in the name and in the person of Christ the Head in the midst of the community.
1592 The ministerial priesthood differs in essence from the common priesthood of the faithful because it confers a sacred power for the service of the faithful. The ordained ministers exercise their service for the People of God by teaching (munus docendi), divine worship (munus liturgicum) and pastoral governance (munus regendi).
1593 Since the beginning, the ordained ministry has been conferred and exercised in three degrees: that of bishops, that of presbyters, and that of deacons. The ministries conferred by ordination are irreplaceable for the organic structure of the Church: without the bishop, presbyters, and deacons, one cannot speak of the Church (cf. St. Ignatius of Antioch, Ad Trall. 3,1).
1594 The bishop receives the fullness of the sacrament of Holy Orders, which integrates him into the episcopal college and makes him the visible head of the particular Church entrusted to him. As successors of the apostles and members of the college, the bishops share in the apostolic responsibility and mission of the whole Church under the authority of the Pope, successor of St. Peter.
1595 Priests are united with the bishops in sacerdotal dignity and at the same time depend on them in the exercise of their pastoral functions; they are called to be the bishops' prudent co-workers. They form around their bishop the presbyterium which bears responsibility with him for the particular Church. They receive from the bishop the charge of a parish community or a determinate ecclesial office.
1596 Deacons are ministers ordained for tasks of service of the Church; they do not receive the ministerial priesthood, but ordination confers on them important functions in the ministry of the word, divine worship, pastoral governance, and the service of charity, tasks which they must carry out under the pastoral authority of their bishop.
1597 The sacrament of Holy Orders is conferred by the laying on of hands followed by a solemn prayer of consecration asking God to grant the ordinand the graces of the Holy Spirit required for his ministry. Ordination imprints an indelible sacramental character.
1598 The Church confers the sacrament of Holy Orders only on baptized men (viri), whose suitability for the exercise of the ministry has been duly recognized. Church authority alone has the responsibility and right to call someone to receive the sacrament of Holy Orders.
1599 In the Latin Church the sacrament of Holy Orders for the presbyterate is normally conferred only on candidates who are ready to embrace celibacy freely and who publicly manifest their intention of staying celibate for the love of God's kingdom and the service of men.
1600 It is bishops who confer the sacrament of Holy Orders in the three degrees.
English Translation of the Cathechism of the Catholic Church for the United States of America © 1997, United States Catholic Conference, Inc.