Deacons, or helpers, appear first in the church of Jerusalem, seven in number. The author of the Acts 6 gives us an account of the origin of this office, which is mentioned before that of the presbyters. It had a precedent in the officers of the synagogue who had charge of the collection and distribution of alms. It was the first relief of the heavy burden that rested on the shoulders of the apostles, who wished to devote themselves exclusively to prayer and the ministry of the word. It was occasioned by a complaint of the Hellenistic Christians against the Hebrew or Palestinian brethren, that their widows were neglected in the daily distribution of food (and perhaps money). In the exercise of a truly fraternal spirit the congregation elected seven Hellenists instead of Hebrews, if we are to judge from their Greek names, although they were not uncommon among the Jews in that age. After the popular election they were ordained by the apostles.
The example of the mother church was followed in all other congregations, though without particular regard to the number. The church of Rome, however, perpetuated even the number seven for several generations. In Philippi the deacons took their rank after the presbyters, and are addressed with them in Paul's Epistle.
The office of there deacons, according to the narrative in Acts, was to minister at the table in the daily love-feasts, and to attend to the wants of the poor and the sick. The primitive churches were charitable societies, taking care of the widows and orphans, dispensing hospitality to strangers, and relieving the needs of the poor. The presbyters were the custodians, the deacons the collectors and distributors, of the charitable funds. To this work a kind of pastoral care of souls very naturally attached itself, since poverty and sickness afford the best occasions and the most urgent demand for edifying instruction and consolation. Hence, living faith and exemplary conduct were necessary qualifications for the office of deacon.
Two of the Jerusalem deacons, Stephen and Philip, labored also as preachers and evangelists, but in the exercise of a personal gift rather than of official duty.
In post-apostolic times, when the bishop was raised above the presbyter and the presbyter became priest, the deacon was regarded as Levite, and his primary function of care of the poor was lost in the function of assisting the priest in the subordinate parts of public worship and the administration of the sacraments. The diaconate became the first of the three orders of the ministry and a stepping-stone to the priesthood. At the same time the deacon, by his intimacy with the bishop as his agent and messenger, acquired an advantage over the priest.
Deaconesses, or female helpers, had a similar charge of the poor and sick in the female portion of the church. This office was the more needful on account of the rigid separation of the sexes at that day, especially among the Greeks and Orientals. It opened to pious women and virgins, and chiefly to widows, a most suitable field for the regular official exercise of their peculiar gifts of self-denying charity and devotion to the welfare of the church. Through it they could carry the light and comfort of the gospel into the most private and delicate relations of domestic life, without at all overstepping their natural sphere. Paul mentions Phoebe as a deaconess of the church of Cenchreae, the port of Corinth, and it is more than probable that Prisca (Priscilla), Mary, Tryphaena, Tryphosa, and Persis, whom he commends for their labor in the Lord, served in the same capacity at Rome.
The deaconesses were usually chosen from elderly widows. In the Eastern churches the office continued to the end of the twelfth century.