What is a...

Preacher. Elder. Deacon. Bishop. Overseer. Shepherd. Pastor. Evangelist. Minister. What do these terms actually mean? We hear them all used in the church and in the religious world at large. Let us look briefly at what the scriptures teach about each of these designations. Greek words and definitions are taken from Vine's Complete Expository of Old and New Testament Words.

Preacher:
kērux, meaning “a herald”
A preacher is a person who preaches. His role is to preach the word, in season and out of season, and to speak the whole gospel of God. His role is not one of guiding or shepherding a congregation. It is necessary for such a person to be careful to speak only God's word, and nothing else in his teaching, because preaching anything else is false teaching.

(II Timothy 4:2, Acts 20:27)

Evangelist:
euangelistēs, meaning “a messenger of good”
This is a term refers to the same person as the preacher, but usually with an emphasis on those reaching outside the church. An evangelist much seek the lost, working to bring the gospel to those who have not yet obeyed Christ.

(II Timothy 4:5, Acts 21:8)

Minister:
daikonos, meaning “a servant, attendant”
leitourgos, meaning “one who discharged a public office at his own expense”
hupēretēs, meaning “an under rower”
A minister is one who works in some capacity (physical or spiritual) for the good of another. All Christians are called to minister to various people: to each other, and to the world. Although a preacher, a deacon, or an elder are all to be a minister, they are not “The Minister.”

(II Corinthians 8:1-4, Romans 15:24-29)

Deacon:
daikonos, meaning “a servant, attendant”
The word for deacon literally means servant. A deacon is one who works in taking care of a congregation's physical day to day things, so that the elders of a congregation may remain focused on the spiritual guidance of a congregation. It is a role which the Bible provides specific qualifications for: grave, not slanderers, sober, faithful, and overseeing their household well (including children and one wife).

(I Timothy 3: 8-13, Acts 6:1-7)

Elder, Bishop, Overseer, Shepherd, Pastor:
presbuteros, meaning “an old man, an elder”
episkopos, meaning “an overseer”
poimēn, meaning “a shepherd, one who tends herds or flocks”
These terms all refer to the same role, which we usually refer to as an elder. Elders are responsible for overseeing the spiritual well being of a local congregation. They are to shepherd their flock, and only their flock, working to ensure that all those under their care are faithfully following Christ. It is a role which the Bible gives quite specific qualifications for. They are men that must be above reproach, husband of one wife, temperate, sober-minded, orderly, given to hospitality, apt to teach, not a brawler or striker, gentle and uncontentious, not a lover of money, rules well his house and believing children, not a new convert, a good reputation outside of the church, and one who holds to that which is good and faithful. Specific guidelines are also set down by God for their oversight to ensure that elders to not begin lording it over a congregation or altering what God has said.

(Titus 1:5-9, I Timothy 3:1-7, I Peter 5:1-3, Acts 20:28-30)