Like the Pentateuch, Isaiah has also received significant scholarly scrutiny. This occurs because of its numerous prophecies about Israel, Babylon, and the Messiah.
The author is identified as Isaiah, son of Amoz (Isaiah 1:1: “The vision concerning Judah and Jerusalem that Isaiah son of Amoz saw during the reigns of Uzziah, Jotham, Ahaz and Hezekiah, kings of Judah.”). That pinpoints the writing to the period from 790 BC through 686 BC, at least 100 years before the fall of Jerusalem to the Babylonians and the resulting exile of 70 years. Isaiah extensively prophesied about this event as well as about God’s judgment on the Assyrians (who conquered the Northern Kingdom of Israel in 722, during Isaiah’s lifetime) and on the Babylonians.
Because liberal scholars are skeptical about anything that points to supernatural inspiration of the Bible, they have tried to explain the fulfilled prophecies in these books by re-dating them to after the events. The theory of Deutero-Isaiah (or Second Isaiah) emerged near the end of the eighteenth century. According to this theory, Isaiah himself wrote only the first 39 chapters, leaving one of his students to pen the second part (chapters 40-66) after the Babylonian captivity started (so, after 586 BC). This later date would explain explicit predictions of “Cyrus, King of Persia” in Isaiah 44:28-45:1.
The Deutero-Isaiah theory claims Isaiah chapters 40-55 contain no personal details of the prophet Isaiah, in strong contrast to Isaiah 1-39. The first section relates numerous stories of Isaiah, especially his dealings with kings and others in Jerusalem. The style and language of Isaiah 40–55 are said to be quite different from the earlier chapters (interestingly, an argument for similarity of styles is advanced by scholars who support one author for Isaiah). The assertion is, that specific references to Cyrus originated in the experiences of the exiles in Babylon. This last argument is supposedly the strongest, yet it seems more wish than fact! It claims the second part of the second part of Isaiah was written later because only a later date can explain the accuracy of the prophecy.
Many scholars rejects the Deutero-Isaiah theory. A long list of arguments includes the similarity of writing styles in both sections, the consistent use of the same words throughout, and the familiarity of author is with Palestine, but not Babylon. Jewish tradition uniformly ascribes the entire book to Isaiah. The Dead Sea Scrolls contain a complete scroll of Isaiah dated from the second century BC that indicates the book as one unit (the end of chapter 39 and the beginning of chapter 40 are in one continuous column of text). Evidently scribes who produced this scroll never doubted the singular unity of the book. Neither did the New Testament authors nor the early church, as quotations from both sections are attributed only to Isaiah.
Isaiah contains extensive and explicit prophecies about the coming of the Messiah as well as the life and crucifixion of Christ. Briefly these include:[21] the reign of Christ in the kingdom (2:3–5), the virgin birth of Christ (7:14), the reign of Christ (9:2,7), His rule over the world (v. 4), Christ as a descendant of David (11:1,10), Christ to be filled with the Spirit (v. 2; 42:1), Christ to judge with righteousness (11:3–5; 42:1, 4), Christ to rule over the nations (11:10), Christ to be gentle to the weak (42:3), Christ to make possible the New Covenant (v. 6; 49:8), Christ to be a light to the Gentiles and to be worshiped by them (42:6; 49:6–7; 52:15), Christ to be rejected by Israel (49:7; 53:1–3), Christ to be obedient to God and subject to suffering (50:6; 53:7–8), Christ to be exalted (52:13; 53:12), Christ to restore Israel and judge the wicked (61:1–3).
Messianic prophecy is strong and important evidence for Jesus’ claims to be God. These prophecies cannot be ignored since Isaiah’s writings were completed many centuries before Jesus Christ was born. Remember, the Dead Sea Scrolls contained more than one complete scroll of this book composed well before the birth of Christ. And the book of Isaiah was included in the LXX translated at least 300 years earlier.
Source