Actually, we can gain a great deal from Isaiah without determining whether each verse is to be interpreted "literally" or "figuratively." Those categories may not even be very well defined in our own minds. To hear of "non-literal fulfillment of Isaianic prophecy in the life of Jesus," might carry a negative connotation for some. Figurative, or non-literal, sounds too much like "non-real" or "not-actual" fulfillment.
One of my presuppositions is that the word "prophecy" as used in scripture means as much about "forth telling" as it does about "foretelling."
"Forth telling" would be more about God setting forth the truth for a more accurate view of reality to those who will listen. Whereas "foretelling" would be more about a sign that God is able to "predict" specific events.
The more we are fixed on the "foretelling" aspect of prophecy the less comfortable we may be with much of the figurative expression which the prophets use to richly "forth tell" a true view of past ,present, and future reality.
God is the one who truly and absolutely both foretells and forth tells. The predictive element of foretelling is meant to be a sign pointing us along to the truth about reality that God is "forth telling." So that the most important emphasis in reading a book like Isaiah should be upon it's effective portrayal of the truth as God has purposed to exhibit it.
Consider the sense in which this prophetic passage either was, or was not, fulfilled in the earthly ministry of Jesus Christ.
Then Jesus *said to them, "You will all fall away because of Me this night, for it is written, 'I WILL STRIKE DOWN THE SHEPHERD, AND THE SHEEP OF THE FLOCK SHALL BE SCATTERED(Matthew 26:31 from Zechariah 13:7).'
Notice that we do not generally think that Jesus must come back a second time as a literal shepherd, with literal sheep, in order for this passage to be truly fulfilled.
Was the passage fulfilled literally? No. Jesus was a traveling Rabbi, we have no reason to think that he was ever a literal Shepherd with literal sheep.
But was this passage fulfilled? Absolutely. And we find ourselves desiring to say, "it was literally fulfilled," because our habit of mind is such that we recognize its figurative fulfilment as its absolute fulfilment. And the truth of Zechariah is confirmed not only in a single, literally fulfilled, passage but also in the whole richly expressed message of what God will accomplish; especially that which God will accomplish through the Gospel.
Even when a specific fulfilment stands out to us because of a literally predictive element, shouldn't our greater appreciation be in the truth the sign points to? For example, in Matthew 21 we find this passage:
[Jesus]saying to them, "Go into the village opposite you, and immediately you will find a donkey tied there and a colt with her; untie them and bring them to Me. "If anyone says anything to you, you shall say, 'The Lord has need of them,' and immediately he will send them." This took place to fulfill what was spoken through the prophet: "SAY TO THE DAUGHTER OF ZION, 'BEHOLD YOUR KING IS COMING TO YOU, GENTLE, AND MOUNTED ON A DONKEY, EVEN ON A COLT, THE FOAL OF A BEAST OF BURDEN.'" The disciples went and did just as Jesus had instructed them, and brought the donkey and the colt, and laid their coats on them; and He sat on the coats(Matthew 21:2-7 from Zechariah 9:9).
Now this specific-predictive fulfillment is certainly an attention getting sign about Jesus the Messiah. But part of its purpose is to point us to the whole of what Jesus Christ's life and ministry fulfilled? The prophet has more broadly portrayed the truth and widespread effect of Christ's work.
Rejoice greatly, O daughter of Zion! Shout in triumph, O daughter of Jerusalem! Behold, your king is coming to you; He is just and endowed with salvation, Humble, and mounted on a donkey, Even on a colt, the foal of a donkey. I will cut off the chariot from Ephraim And the horse from Jerusalem; And the bow of war will be cut off. And He will speak peace to the nations; And His dominion will be from sea to sea, And from the River to the ends of the earth(Zechariah 9:9-10).
Why did Jesus come to Jerusalem in humility on a donkey? As a sign that his work of gentleness and submission conquers that which could not be conquered by proud and violent horsemen. And so He "cut off the chariot from Ephraim And the horse from Jerusalem." He "cut off the bow of war" from His people and spoke peace to the Gentiles.
Well, anyway, I hope you will enjoy your reading of Isaiah with a growing appreciation for the glorious way in which God brings it to fulfillment.
Yours,
Jeff