The custom of confessing before a priest originated in the early Christian period, when public forms of repentance were first practiced, and gradually underwent significant transformations.

Evolving Rituals: The Transformation of Confession in Early Christiani

The custom of confessing before a priest originated in the early Christian period, when public forms of repentance were first practiced, and gradually underwent significant transformations.

Initially, confession had a collective, even communal character. As stated in one source:
"Sometimes public confession before the entire community was practiced (by the 5th century it disappeared), as well as confession before several priests. More often, however, confession was private.

In the Christian tradition, the Church is perceived as a spiritual 'clinic', sin as a disease, confession as treatment, and the priest as a doctor: 'Have you sinned?

Enter the church and repent of your sin... Here the priest is a doctor rather than a judge; here no one is condemned, but everyone receives absolution' (Saint John Chrysostom). The rite of confession preserves the words: 'Listen, for you have come into the clinic so that you may not leave unhealed'" (source: link txt).

Over time, especially with the rise of monasticism, confession began to take on a more individual and personal character. In monastic life, obedience and total surrender to the spiritual mentor were of great importance. This is noted as follows:
"The foundation of monasticism is obedience, manifested as a complete surrender of the disciple’s will to his spiritual mentor. Spiritual guidance in the monastery began to be carried out through the confession of one’s thoughts to the elder, the spiritual director. This was accompanied by a spiritual ascetic struggle" (source: link txt).

The evolution of confession was also reflected in its timing with the most important church feasts. One testimony notes that:
"The celebration was usually linked to Great Thursday, Friday, or the Sabbath of Passion Week. If the sinner had been given over to Satan to weaken the flesh—so that the spirit might be saved, or if he had entrusted himself to him—then the bishop, reconciling him with the Church, would have all those present pray for him. After this, the sinner—or rather, the now saint—was finally admitted to the long-desired union with Christ in the sacrament of Holy Communion and became a full member of the community" (source: link txt).

Thus, while confession initially served as a public act of repentance and was an integral part of communal Christian life, by the 5th century it had shifted to a more private, individual practice. The establishment of monasticism and the development of spiritual guidance greatly influenced the transformation of this rite, enhancing its personal and ascetic dimensions. Later developments included the compilation of special lists of sins accompanied by designated penances, which further systematized the rite of confession within church practice.

Thus, the evolution of the practice of confession in the Christian tradition reflects a transition from a communal practice to a more intimate, personalized form that has adapted to the spiritual and ecclesiastical needs of the faithful over the centuries.