John Calvin Commentary 1 Timothy 3:8

"Deacons in like manner [must be] grave, not double-tongued, not given to much wine, not greedy of filthy lucre;" — 1 Timothy 3:8 (ASV)

Likewise the deacons. There is no reason why the diversity of interpretations should lead us to entertain any doubt. It is certain that the Apostle speaks of those who hold a public office in the Church; and this refutes the opinion of those who think that domestic servants are meant here.

As for the view given by others, that it denotes presbyters who are inferior to the bishop, that is without foundation; for it is clear from other passages that the term bishop belongs equally to all presbyters. All are constrained to acknowledge this; and more especially, a passage in the first chapter of the Epistle to Titus clearly proves that this is the meaning (Titus 1:7).

It remains to be stated that we understand "the deacons" to be those who are mentioned by Luke (Acts 6:3), and who had the charge of the poor. But those who wish to have a more complete account of the duties of deacons may consult the Institutes.

Grave, not double-tongued. The first four virtues with which he wishes them to be endowed are sufficiently well known in themselves. Yet it ought to be carefully observed that he advises them not to be double-tongued; because it is a vice that is difficult to avoid in the discharge of that office and yet, more than anything else, ought to be kept at a distance from it.