Most biblical scholars do not affirm that the entire Book of Isaiah was written by the prophet Isaiah who lived at the end of the eighth and beginning of the seventh century B.C. I am one of those traditionalist that finds the arguments against a unified authorship unconvincing and therefore willing to assume the claims of tradition. At the end of the day it is the canonical standing of the book that really matters, but I find a unified authorship has less theological problems and no less historical problems.

Bryan E. Beyer does a good job of presenting both sides of the debate in Encountering the Book of Isaiah: A Historical and Theological Survey (153-161):


(1) Time span: Is. 1-39 cover Judah’s troubles with Assyria while 40-66 focus upon Babylon. It would appear that whoever wrote 40-66 did not share the immediate concerns of whoever wrote 1-39. Whoever wrote the second part was around during Babylon’s empire.

(2) Subject matter: Also, in 40-48 King Cyrus of Persia is mentioned by name a couple of centuries before he came to power. This seems unlikely and the more natural explanation would be that the author was a contemporary of those events. It is rare for biblical prophecy to be that precise.

(3)  Vocabulary and style: The author of 1-39 wrote a lot of narrative, many oracles, and some poetic passages, but none that were as detailed and rich as 40-66. The tune has changed as well. In 1-39 it is a bit pessimistic, while 40-66 are uplifting and hopeful.

There is no arguing against the fact that it is more logical that someone would have been in Babylon, watching the rise of Cyrus of Persia, who was a more poetic writer addressing a more hopeful time. It is not absurd to hold to multiple authors and there are even many evangelicals who do. I do not and I think Beyer’s reasons for singular authorship are convincing.

Singular author:

(1) Predictive prophecy: Of course, if God sees the future it is altogether possible that he could have told the prophet about Cyrus and the eventual fall of Babylon. In chapter thirty-nine we have Isaiah predicting Babylon’s rise at a time when Assyria was still the dominant power in the Near and Middle East.

(2) Different subject matter: There is nothing preventing the prophet Isaiah from finishing his own book on a hopeful note. There is no reason that he could not have written such amazing poetry and why couldn’t he have been the one to have these visions? It does seem odd, as Beyer notes, that if there is another author of 40-66 he disappears into history unknown while the lesser skilled prophet remains a prominent historical figure.

(3) Different vocabulary and style: Again, if the context of what Isaiah is addressing has changed, and he wants to end his own work with hopeful visions of the future, why could he not have written differently?

(4) Lack of chronological order: As I mentioned in my post a few days ago (see here) the chronological order of chapters 36-39 doesn’t match the literary order. It seems that Isaiah intentionally told a story about Babylon after telling some stories that happened later because he intended to tie it into 40-66’s address of Babylon’s future. Beyer notes at 2 Kings 18-20 does this very same thing even though it tends to go along a strict chronology when possible. He even argues that the author of 2 Kings 18-20 may have had access to Is. 36-39.

(5) Textual evidence: There has never, ever, ever been a transcript of the Book of Isaiah either lacking 40-66 or hinting that 1-39 and 40-66 were two books. Singular authorship has been assumed by Jews and Christians until the last two hundred years.

(6) NT quotations: There are several quotations in the NT that come from 40-66 that mention Isaiah as the author, e.g.:
– Is. 40.3 in Mt. 3.3
– Is. 40.3-5 in Lk. 3.4-6
– Is. 42.1-4 in Mt. 12.17-21
– Is. 53.1 in Jn 12.38
– Is. 53.4 in Mt. 8.17
– Is 65.1-2 in Rom. 10.20-21

Honestly, this often comes down to various premises related to Isaiah’s vision of Cyrus in my opinion. I am not saying this is the only motive for denying singular authorship, but likely the first and foremost. Of course, if you believe in a future seeing God then why couldn’t Cyrus be mentioned by name? Also, if you do not believe in a future seeing God that could name Cyrus what hope do we have that any of the visions of the new heaven and new earth in the age to come are of any worth?