Why is a priest necessary for hearing confession?
The relevant Catholic doctrine is described in the “Catechism of the Catholic Church” under the heading: sacramental penance
The gospels report that Jesus has forgiven individual people their sins: Your sins are forgiven (Mk 2:5; Lk 7:48). He has also given this authority to the people (Mt 9:8). The Church as a whole is to be a sign and a tool of reconciliation. In a special way, however, this authority has been given to the apostolic office, i.e. to the apostles and their successors. It has been tasked with the service of reconciliation (cf. 2 Cor 5:18); on behalf of Christ, as though God was making his appeal through us: .... be reconciled to God. (2 Cor 5:20). Therefore the Church traces the authority of its office of the forgiveness of sins to the risen Lord himself: “Receive the Holy Spirit. If you forgive the sins of any, they are forgiven them; if you retain the sins of any, they are retained”. (Jn 20:22-23)
For Jesus, the forgiveness of sins always had a community aspect. Jesus reconciles sinners with God by taking them up into the Eucharistic community with him and with each other. The sinner isolates himself from God and from the brothers. Through his sin the communion of the people of God is marred and the holiness of its life lacerated. The sinner is therefore excluded from the full communion of the Church (cf. 1 Cor 5:1-13; 2 Cor 2:5-11; 7:10-13); in particular, he is no longer able to participate fully in the holy Eucharist, the sacrament of unity and love. Through the confession the repenting person has to retrace the path on which reconciliation first came to him. He has to reconcile himself with his brothers in order to achieve renewed communion with God. By the same token, God’s forgiveness reconciles us also with the Church, that was wounded by the sin and that aids the conversion through love, example and prayer (LG 11). This communal structure and the Church dimension of penance is particularly clearly seen in Jesus words to Peter: ”I will give you the keys of the kingdom of heaven, and whatever you bind on earth shall be bound in heaven, and whatever you loose on earth shall be loosed in heaven” (Mt 16:19).
This also applies to the Church as a whole (c.f. Mr 18:18). The words binding and loosing mean: whoever you exclude from your community (binding = banishing), is also excluded from the communion with God; but whoever you take up again into your community (= loosing the ban), God also takes up into Communion with him. Reconciliation with the Church is thus the path to reconciliation with God. This aspect was particularly clearly expressed in the public penance in the ancient Church. Correspondingly the formula for sacramental absolution that has been compulsory since 1975 says: May He grant you pardon and peace through the ministry of the Church.
The sacrament of penance has had a varied history with many changes. A two-fold process has consistently been the main structure of this sacrament: The sacrament of penance consists on the one hand of human acts of conversion made possible by grace; repentance, confession and reparation. On the other hand, it consists of the acts of the Church, because the church community led by the bishops and priests offers the forgiveness of sins in the name of Jesus Christ, determines the necessary reparation, prays for the sinner, vicariously repents for him and finally grants him the full communion with the Church and the forgiveness of his sins. The sacrament of penance is thus a wholly personal act as well as a liturgical celebration of penance by the Church. The Council of Trent therefore teaches that the actions of the repentant sinner in penance, confession and reparation are quasi the substance of the sacrament, while the absolution by the priests represents the form of the sacrament of penance (cf. DS 1673; NR 647-648). The fruit of this sacrament is the reconciliation with God and with the church. It is often accompanied by peace, a joyful conscience and enormous comfort of the soul (c.f. DS 1674-1675, NR 649).
Let us try to describe the individual elements of sacramental penance in more detail. The primary action of the penitent is contrition. It is the pain of the soul and the revulsion at the sin committed, with the resolve to sin no more from now on. This contrition is called perfect contrition when it is caused by Gods love (Latin: contritio). Such contrition has the power to grant forgiveness of every day sins; it also results in the forgiveness of serious sins if it is combined with a firm resolve of sacramental confession. Contrition is called imperfect, if it arises from considerations about the ugliness of the sin or from the fear of eternal damnation and other punishment (attrition). Such a shaking up of the conscience can merely be a beginning which is perfected by the (369) gift of grace, in particular the forgiveness of sins in the sacrament of atonement (cf. DS 1676-78, NR 650-651).
From a human point of view alone the confession of guilt has a liberating and reconciling effect. Through the confession a person faces his sinful past and takes responsibility for it, and opens himself again to God and to the communion of the church and therefore gains a new future. According to the doctrine of the Church such a confession is an important and indispensable part of the sacrament of penitence in order to submit oneself to Gods merciful judgement (cf. DS 1679; 1706; NR 652; 665). It is therefore necessary to confess the major sins (mortal sins) one can remember after careful examination of ones memory, in such a way that the actual situation in terms of numbers, characteristics and circumstances is adequately expressed (cf. DS 1707; NR 666). According to Canon law, every believer having reached the age of discernment is required to confess his serious sins with sincerity at least once a year (CIC can. 989). Confessing every day sins (venial sins), which do not exclude us from communion with God is not necessary, but is recommended by the church as useful. This devotional confession is an important aid in the formation of a personal conscience and the growth in spiritual life. It is therefore highly recommended and should have a place during Lent (the penitential season of the Church) once every year at least.
The purpose of restoration is to redress as far as possible the damage and the vexation caused by the sin in an appropriate manner (e.g. returning of stolen goods, restoration of the reputation of others). Restoration is also an exercise in a new way of life; it is a remedy against weakness. The actual restoration should therefore correspond as far as possible with the severity and the characteristics of the sins. It can consist in prayer, sacrifice, renunciation, the service of others, and in merciful acts. Such a restoration is not an achievement by the individual achievement which earns him forgiveness; rather, it is a fruit and a sign of the penitence granted and effected by the Gods spirit (370). The absolution spoken by the priest during the sacrament of penitence is not merely a proclamation of the gospel of the forgiveness of sins, or a statement that God has forgiven the sins; the doctrine of the church states that as the a readmission into the full communion of the church, it is an act of judgement that can only be dispensed by someone who can act in the name of Jesus Christ for the whole communion of the Church (cf. DS 1685; 1709-1710; NR 654; 668-669). The sacrament of penitence is, however, a merciful judgement, in which God the merciful Father in the Holy Spirit confronts the sinner with grace because of the death and resurrection of Jesus Christ. In the same way, the confessor assumes the role of a judge as well as the role of a doctor. He is required to act like a father and a brother. He represents Jesus Christ who on the cross gave his blood for sinners. He should therefore proclaim and explain to the confessing person the message of the forgiveness of sins and shall advise him in order to help him toward a new life, pray for him and vicariously repent for him, and finally absolve him of his sins in the name of Jesus Christ.
Since the amendment of the Celebration of Penitence in 1974 there have been three forms of the sacramental celebration of penitence:
Form A: Celebration of reconciliation for individuals. This form too should have a certain liturgical structure: welcome by the priest, a reading from Scripture, confession of sin, imposition of penance, prayer, spreading of the priest’s hands with absolution followed by giving thanks and liturgical dismissal with priestly blessing. For pastoral reasons the priest can omit or shorten parts of this rite, however, the following parts must remain in full: the confession of sins and the acceptance of the imposition of penance, the request for contrition, the absolution and the dismissal. Where there is danger of death it is sufficient if the priest’s says the main words of the absolution: I absolve you from your sins in the name of the Father, the Son and the Holy Spirit. In practice, however this new form of the sacrament of penitence has not been generally adopted.
Form B: Corporate celebration of reconciliation with confession and absolution of the individual. This form combines the individual confession and absolution with a corporate celebration of penitence for the preparation and corporate thanksgiving. The individual confession is thus embedded in a liturgical service with the reading of Scripture and a homily, corporate search of the congregation’s conscience and general confession of sins, prayer, the Lord’s Prayer and corporate thanksgiving. This congregational celebration makes the corporate church character of penitence clearer. (371)
Form C: The corporate celebration of reconciliation with general confession and general absolution. This form is only permitted if there is an urgent need. Apart from the danger of death, this need only arises when there is an insufficient number of confessors, so that there is not enough time to adequately hear the confession of the individual, and they would otherwise and not by their own fault have to remain for longer without the grace of the sacraments or of holy Communion. This presupposes the will to confess mortal sins as soon as possible on an individual basis. The decision whether there is such an urgent need is the responsibility of the diocesan bishop who consults the other members of the Bishops Conference (cf. CIC can. 961). The German Bishops Conference currently does not believe there is such an urgent need, with the exception of danger of death of a larger group.
These three forms of the sacramental celebration of penitence are not the same as services of penitence in the narrower sense. The services of penitence are expression and renewal of the conversion effected at Baptism. At those services the people of God gather to hear the Word of God, which calls for conversion and the renewal of life, and which proclaim the deliverance from sin through the death and resurrection of Jesus Christ. Such a service of penitence consists of: Introduction (singing, welcome and prayer), readings from Holy Scripture interspersed by a hymn or by silence, a homily, the corporate searching of the congregations conscience and prayer for the forgiveness of sins, in particular the Lord’s Prayer, but no sacramental absolution. These services of penitence must therefore not be confused with the celebration of the sacrament of penitence. They are, however, very useful for the conversion and purification of the heart. They can promote the spirit of Christian penitence and can help the believers in the preparation of their individual confessions, deepen the sense of the corporate character of penitence and in particular, lead children towards penitence. If there is a real spirit of conversion and perfect contrition, the forgiveness of venial sins is granted during such services of penitence. Such a service is also an effective means of salvation. It should be part of the life of every parish and should be celebrated in particular during Lent, the penitential season. (cf. Gem. Synode, Schwerpunkte heutiger Sakramentenpastoral C 4). („Katholischer Erwachsenen-Katechismus“ (Catholic Adult-Catechism, published by tehGerman Bishops Conference), Band 1, pp. 367-371)