In non‐Christian Greek the word is used of officials who act on behalf of rulers, with their authority, such as ambassadors or heralds. Hermes is called a ‘deacon’, diakonos, because he carried out the commissions of the gods. Paul is a diakonos of God as being his authoritative mouthpiece. What is common to the various functions is their mediatorial work—Paul is an ambassador to the Gentiles, a reconciler between the two branches of the Church, Gentile and Jewish, holding them in unity through his collection for Jerusalem and at the same time urging ex‐Jews to accept his principles i.e. of separation from the institutions of Judaism.
The deacons in the Church are to embody personal integrity and their role is that of a scribe, whereas the task of teaching is entrusted to the presbyter—bishops (1 Tim. 3: 2, 5). From Rom. 16: 1, where Phoebe is mentioned, it would seem that in the NT women could be regarded as deacons.
It has often been supposed that the Seven appointed to assist the Twelve (Acts 6: 1–6) were the first deacons, since their function was to minister (Greek, diakonein), and ‘serve tables’, but in the event Stephen and Philip engage in evangelistic enterprises on their own account, and the Seven were more the antecedents of the presbyterate than the Church's diaconate. The functions of the latter were administrative and liturgical in the early Church, but they were not inferior officers. They acted as the bishop's agents, and they remained deacons for life. Only as the presbyters, under local pressures, gradually assumed some of the bishops' functions did the diaconate in the West become less important. At last, in the Middle Ages, the diaconate became merely a probationary stage on the way to the priesthood (presbyterate).
When Jesus is recorded as saying that he came ‘not to be served but to serve’ (Greek, diakonein, Mark 10: 45), the meaning is that he is not the kind of great person in the world who has agents around to go out and do his bidding; he has his own duties to do himself.