Here is how their argument goes: Isaiah 1-39 and 40-66 are so different in their content that they simply cannot have been written by the same person. The first section is full of judgment and the second full of comfort. The first section is all about sin and retribution, whereas the second is all about salvation and redemption. The first section is all about Judah and Assyria, whereas the second is all about Zion and Babylon. What is more, Isaiah uses by far the largest Hebrew vocabulary in the Old Testament (almost 2,200 different words) and there are subtle differences between his choice of words in the two sections. To top it all, these scholars argue that several of the prophecies in the ‘Book of Comfort’ are so insightful about the future that they must have been written in retrospect rather than ahead of time. They find it particularly hard to believe that Isaiah could have named Cyrus as the Persian king who would capture Babylon and send the Jewish exiles home, if he were prophesying a hundred years before Cyrus was born.

As a result, many Old Testament scholars state categorically that there must have been more than one Isaiah. They try to saw Isaiah in two by describing the author of the ‘Book of Judgment’ as ‘Proto-Isaiah’ (‘the first Isaiah’, chapters 1-39) and the author of the ‘Book of Comfort’ as ‘Deutero-Isaiah’ (‘the second Isaiah’, chapters 40-66). A few scholars even go one step further and saw Isaiah in three by citing further textual differences between chapters 40-55 and chapters 56-66, thereby creating an additional ‘Trito-Isaiah’ (‘the third Isaiah’). Many Christians either nod at this too easily or dismiss the very idea far too quickly. The truth is, it really matters to the meaning of the whole book of Isaiah. That’s why I want to give you four reasons to be confident about the unity of the book of Isaiah as a whole.

First, the differences have been dramatically overplayed. One of the big themes of Isaiah is to call the Lord “the Holy One of Israel.” Isaiah uses this name 12 times in Isaiah 1-39 and 14 times in Isaiah 40-66. Another big theme is Zion, which is named more often in Isaiah than in any other book of the Bible: 31 times in Isaiah 1-39 and 18 times in Isaiah 40-66. The differences in vocabulary have also been exaggerated, and what differences there are can be explained by the fact that Isaiah completed the ‘Book of Comfort’ by the end of 701BC and then continued to prophesy for at least a further fifteen years. There are at least 25 words which are used nowhere in the Old Testament except in Isaiah, but which are used in both halves of his book of prophecies. Isaiah’s vocabulary points to unity, not disunity. We can even see the unity of this book of prophecies in the way in which both sections start and end. They both begin with the old city of Jerusalem (1:1 and 40:2) and they both close with God’s new city on Mount Zion (35:10 and 66:20).

Second, it’s worth noting that those who seek to saw Isaiah in two have the heavy weight of history stacked against them. There is not a single ancient manuscript of Isaiah, either in Hebrew or in Greek, which is divided in the manner they expect. To put it mildly, this is a very major weakness in their theory. When a shepherd-boy discovered the Dead Sea Scrolls in 1947, one of those two-thousand-year-old scrolls was the book of Isaiah set out as one seamless book of prophecies. Add to this the testimony of the famous Jewish rabbi Ben Sira in around 200BC (Sirach 48:20-25) and that of the Jewish historian Josephus in around 95AD (“Antiquities of the Jews”, 11.1), and the weight of evidence stacked against their theory is devastating.

Third, we should really not be surprised that Isaiah foretold the future so accurately. Predicting the future is, after all, precisely what the prophets claimed that God had given them the supernatural ability to do! John 12:37-41 particularly draws our attention to Isaiah’s amazing insights into the future, not to deny them but to warn us not to be like his stubborn contemporaries who refused to take his words seriously. His predictions about Cyrus should not make us try to saw him in two. They should make us marvel that it means that all his other prophecies will just as surely all come true.

Fourth, Jesus and the writers of the New Testament bear united testimony that Isaiah wrote the entire book. For me this is the absolute clincher. John 12:37-41 quotes from both sections of Isaiah and attributes both quotes to a single author. So do Matthew 3:3 and 4:14, Mark 1:2 and 7:6, Acts 8:30 and 28:25, and Romans 9:27 and 10:16. In fact, the New Testament is so clear about this and so often that the failure of so many scholars to recognise it seems to illustrate the truth of Isaiah 29:14: “The wisdom of the wise will perish, the intelligence of the intelligent will vanish.”

All of this matters. When we recognise that Isaiah’s ‘Book of Comfort’ is the sequel to his ‘Book of Judgment’, it actually makes an enormous difference. It helps us understand what he means when he begins his second section with the words, “Comfort, comfort my people, says your God. Speak tenderly to Jerusalem, and proclaim to her that her hard service has been completed, that her sin has been paid for.” It means that Isaiah is announcing that he is moving on from words of judgment to words of comfort. He is about to prophesy what the Messiah has done to earn our forgiveness and to turn us into the New Jerusalem.

Recognising the integrity of the book of Isaiah also helps us understand what the prophet means when he continues, “A voice of one calling: ‘In the wilderness prepare the way for the Lord; make straight in the desert a highway for our God … The glory of the Lord will be revealed, and all people will see it together.’” All four gospels quote from these verses and apply them to the ministry of John the Baptist, the one who preached in the desert that people needed to be baptised in preparation for the imminent revelation of God’s Messiah. In addition to prophesying about him, these verses also describe the whole of Isaiah 1-35 as a kind of John the Baptist for us too. The first half of this book has prepared us for a detailed revelation of the Messiah in the second half of the book. It has cleared away the rough ground so that God can build his holy highway for all people.

So let’s not separate what God has joined together. The 66 chapters of Isaiah flow together as a single whole. Everything that God whetted our appetite for in Isaiah 1-35 is about to be revealed as ours through faith in his glorious Messiah in Isaiah 40-66.

“Comfort, comfort my people, says your God.” Knowing that there was only one Isaiah helps us to understand that God’s words of judgment are over. We are about to receive real comfort indeed.

This chapter is taken from Phil Moore’s new book “Straight to the Heart of Isaiah”, which is now in bookstores. To read more chapters, go to www.philmoorebooks.com