The third category of
"faithful people" is diakonos, deacon.
1 Timothy 4:6,13,16
If you will give these instructions to the brothers, you
will be a good minister (diakonos)
of Christ Jesus,
nourished on the words of the faith and of the sound
teaching you have followed. ... Until I arrive, attend
to
the reading, exhortation, and teaching. ... Attend to
yourself and to your teaching; persevere in both tasks,
for by doing so you will save both yourself and those
who listen to you.