The notion of biblical poetry is the invention of 18th centry Anglican Bishop Robert Lowth.

To read something as sweepingly magnificent as Isaiah 2:1-5 (OT lesson for Advent 1 Series A), and to name it poetry neither means anything nor advances anything, but only nominalizes Scripture. 

But to call it what it is, liturgy, is to say a mouthful. To consider the Scriptures to be anything less than God's words, put on human lips, by which which we proclaim his gospel aloud, is to cut them down to size.

Scripture is not literature even if it is composed of letters. To assert that it is is to commit the logical fallacy of composition. This is not literature, but liturgy. These are God's words that were not just written down as divine information, but that were given us by God's prophet Isaiah so that we might pray them, and in this way worship him in Spirit and Truth. 

As Christians we are like infant children who spend years hearing their parents' language and then one day reciprocate by speaking it back to them. Now the circuit is complete. In like manner God and man who were once alienated by sin, are on the same page, now on speaking terms once again, speaking holy words.

The King James Bible has mislead Protestants by formatting all of Scripture as though it were narrative. More modern versions versify many of the portions that they (wrongly) recognize as poetry but are actually liturgy. In so far as they do they have done a great service.

I don't know what the exact versification of these verses should be but here is an example. Try praying it antiphonally and you will see that this is its true and natural form.

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The word that Isaiah son of Amos saw concerning Judah and Jerusalem.

It shall come to pass in the latter days that the mountain of the house of the LORD will be established as the highest of the mountains,
     and it will be lifted up above the hills, and all the Gentiles shall stream into it.

And many peoples shall come and they will say:
     "Come! Let us ascend the LORD's mountain,

let us go to the house of the God of Jacob
     that he may teach us his ways, so that we may walk in his paths."

For Holy Instruction (Torah) proceeds from Zion,
     and Yahweh’s Word from Jerusalem.

And he shall judge between the gentiles,
     and decide disputes for many peoples;

And they shall beat their swords into plow blades,
     and their spears into pruning hooks!

Nation shall no longer lift up sword against nation,
     and they shall learn war no more.

O house of Jacob come!
      Let us walk in the light of the LORD.