When was the “Evangelist” title first applied to the Gospel authors?
An exact date is impossible to ascertain, but their are a few glimmers of light on this subject.
First of all, let us look at what it is to be an evangelist in the broadest sense.
Etymology
The word evangelist comes from the Koine Greek word εὐαγγέλιον (transliterated as euangelion) via Latinised evangelium as used in the canonical titles of the Four Gospels, authored by (or attributed to) Matthew, Mark, Luke, and John (also known as the Four Evangelists). The Greek word εὐαγγέλιον originally meant a reward given to the messenger for good news (εὔ = "good", ἀγγέλλω = "I bring a message"; the word "angel" comes from the same root) and later "good news" itself.
The verb form of euangelion, (translated as "evangelism"), occurs rarely in older Greek literature outside the New Testament, making its meaning more difficult to ascertain. Parallel texts of the Gospels of Luke and Mark reveal a synonymous relationship between the verb euangelizo (εὑαγγελίζω) and a Greek verb kerusso (κηρύσσω), which means "to proclaim".
The title of *Evangelist as being first uniquely applied to the Sacred Writers of the four Gospels was in fact something that came about gradually.
At one point this term was used to be given to readers during the sacred liturgy. After all, the priests and deacons were the sacred ministers who read the Gospel at mass!
Gradually it became confined to the writers of the Four Gospels. It is exclusively in this sense that common modern usage employs it.
St. Paul, in his list of the gifts bestowed by Christ for the edification of the Church, Ephesians 4:11 (in 1 Corinthians 12:28, they are omitted), mentions the evangelists in the third place, only after the Apostles and the Prophets. In the writings of the Apostolic Fathers, no reference is made to evangelists; travelling missionaries are sometimes called "apostles", sometimes also, as in the Didache, they are styled "teachers".
In the later ecclesiastical literature the word evangelist, perhaps sporadically still used for some time in its old sense (Eusebius, Church History V.10), received in most parts of the Church, another meaning. Applied occasionally to the reader in the Liturgy (Apost. Const., III), even to the deacon (Lit. of St. John Chrysost., P.G., LXIII, 910), it became gradually confined to the writers of the Four Gospels (Eusebius, Church History III.39, etc.. It is exclusively in this sense that common modern parlance employs it. - Evangelist
Eusebius of Cæsarea, (260-341) Bishop of Caesarea Maritima and Father of the Church, was a historian of Christianity, exegete, and Christian polemicist. He adds the following insights about the title of evangelist in his Church History (Book III):
Chapter 37. The Evangelists that were still Eminent at that Time.
- But since it is impossible for us to enumerate the names of all that became shepherds or evangelists in the churches throughout the world in the age immediately succeeding the apostles, we have recorded, as was fitting, the names of those only who have transmitted the apostolic doctrine to us in writings still extant.
Thus I believe that the term Evangelist only applied to the writers of the four Gospels came about sometime in the late third or early fourth century. This can only be applied to more traditional conservative Christian believers such as Catholics and Orthodox. Some modern denominations employ this term for preachers of one kind or another.