Based on 16:4, this text appears to date from the first third of the 2nd century. It says a lot about Jesus, his divinity, lordship, redemptive death, and resurrection. But everything that it says is based on private revelation and strange, fanciful readings of the Jewish Bible; no Gospel traditions are cited. The Jesus who appears in this epistle is not a recent historical man, but a revealed "son of God."
We ought therefore to be very thankful unto the Lord, for that He
both revealed unto us the past, and made us wise in the present, and
as regards the future we are not without understanding.
What the author says about Jesus:
1) Son of God and Lord of creation, to whom the Father speaks in Genesis 1:26.
2) Judge of the living and the dead
3) Not a "son of man," nor a son of David (12:10)
4) He "came in the flesh" (5:11) and was "manifest in the flesh" (5:6) and "dwelt among us" (6:14)
5) He came to earth to prepare a new people for himself
6) He taught Israel, performed signs and wonders, preached and showed love
7) He selected apostles, 12 of them "as a witness to the tribes" (8:3) to preach his gospel "who were altogether lawless beyond all sin"
8) He allowed himself to suffer by human hands "for our salvation," but also "to total up the sins" of those who killed the prophets (5:11)
9) When he was crucified he was given vinegar and gall to drink (7:3)
10) "The kingdom of Jesus is on the tree" and "blood flows from a tree"
11) He destroyed death and showed that there is a resurrection of the dead
12) He arose from the dead "on the 8th day," appeared, and ascended into heaven
All of these affirmations about Jesus are truths revealed to holy prophets such as the author, but obscure to the Jews.
The Lord dwells in the hearts of the believers and thus reveals his mysteries to them. But events past and future are understood obscurely even by the believers, because they are given in parables:Barnabas 8:7
Now to us indeed it is manifest that these things so befell for this
reason, but to them they were dark, because they heard not the voice
of the Lord.
Thus the basic outline of a story is presented, of the Son of God who assumes flesh and comes to earth and dies at the hands of sinners. Peculiar details like the vinegar and gall appear, but are derived from older and sometimes unknown scriptures.Barnabas 16:8
But [the temple] shall be built in the name of the Lord. Give heed then that
the temple of the Lord may be built gloriously.
How? Understand ye. By receiving the remission of our sins and
hoping on the Name we became new, created afresh from the beginning.
Wherefore God dwelleth truly in our habitation within us. How? The
word of his faith, the calling of his promise, the wisdom of the
ordinances, the commandments of the teaching, He Himself prophesying
in us, He Himself dwelling in us, opening for us who had been in
bondage unto death the door of the temple, which is the mouth, and
giving us repentance leadeth us to the incorruptible temple.
For he that desireth to be saved looketh not to the man, but to Him
that dwelleth and speaketh in him, being amazed at this that he has
never at any time heard these words from the mouth of the speaker,
nor himself ever desired to hear them. This is the spiritual temple
built up to the Lord.
For if I should write to you concerning things immediate or future,
ye would not understand them, because they are put in parables. So
much then for this.
What to make of all this? The story of Jesus is plainly and unequivocally given through revelation to the author, who performs midrash on the OT. There is no trace of "historical traditions" or "oral traditions" connected to the written Gospels (although Ehrman in his translation puts certain verses in quotation as though the author knew that he was quoting one of the Gospels: a historicist presumption). On the other hand, the story is remarkably close to the canonical Gospel history, despite odd details like the utterly depraved apostles, and resurrection-plus-ascension on the 8th day. The author appears to be aware of the Pauline tradition, and speaks in a language and manner highly reminiscent of Paul ("we have been justified" 15:8). But, strangely, he does not identify himself to his readers. Is this a real letter at all, or an early draft by some anonymous scribe?
He assumes Paul's doctrine of redemption, but talks at length about suffering, why the Lord had to suffer, and why the believer too must suffer in order to inherit the kingdom. These themes are not difficult to associate with the Pauline tradition. But now we also have the outline of an incarnation-redemption story, not even a story but the idea of a story.
The Epistle of Barnabas is some kind of link between the Pauline tradition and the Gospel History. Had he known anything of the supposed traditions about Jesus of Nazareth that historicists so confidently assert must have existed in Christian circles circa 120 CE, why would this author, who writes with such authority about the Lord Jesus, know so little about them? (Especially if the common opinion about this text that it comes from a circle in Alexandria is correct; how would the Christians of Alexandria in the 2nd century not know anything about the Jesus story?) And yet he tells the story of Jesus in vague outline.
I think it counts not only as evidence for mythicism, but also as evidence that the Gospel History was unknown to Christians until close to the middle of the 2nd century. It is entirely plausible that the authors of the Gospels used this text as a source. What they have in common is an overriding desire, which we do not find in the Pauline epistles, to blame unbelieving, literal-minded Jews as the enemy of Jesus. The overwhelming desire of Christians at this time was to lay claim to the Jewish covenantal theology and all its authority. The Gospels are the realization of a plan that we see clearly outlined in this epistle.
However, Earl Doherty, whose analysis agrees with my own, notes an important difference between "Barnabas" and the Evangelists regarding what specific theological crime the Jews have committed.