I'm reading and hearing commentaries regularly refer to sections of Paul's writing as poems, for example, Colossians 1:15-20. Why do they call those sections poems?
Paul's uplifting and inspiring words on the supremacy of Christ (in Colossians 1:15-20) have a form of poetry about them. This is the comment in the English Standard Version Study Bible (2008):
In a strongly moving and poetic way, which some scholars think is a quotation from an early Christian hymn, Paul praises the lordship of Christ in relation to both creation and redemption.
The New Living Translation Study Bible (2007) has this to say:
The series of short statements, the exalted conceptions of Christ and the parallelism in language and thought strongly suggest that these verses quote an early Christian hymn that Paul applied to the situation of the Colossian Christians.
The New International Version Study Bible (2000) makes this observation:
Perhaps an early Christian hymn on the supremacy of Christ
This is cross-referenced to Colossians 3:16 where Paul speaks about the Christians singing "psalms, hymns and spiritual songs with gratitude in your hearts to God" where hymn is literally psalm in the Greek text. A hymn (like a psalm) is a song of praise.
Whether the words in Colossians 1:15-20 are viewed either as poetry or as a hymn, they are deeply moving and eloquently express the supremacy of Christ.
Edit: Parallelism is the use of components in a sentence that are grammatically the same; or similar in their construction, sound, meaning, or meter. I found this information on Hebrew poetry but I have no idea if this applies to the word’s Paul wrote in Colossians 1:15-20:
Hebrew poetry does not have rhythm and meter in the same sense as, for example, iambic pentameter verse in Western poetry. Rather, Hebrew poetry seems to be governed by a basic balance between the lines of a couplet (or triplet) whereby each line has the same number of word units. Most couplets have three major stressed word units in each line resulting in a 3 + 3 pattern. In the following example, note that it often takes multiple English words to translate one Hebrew word. Source: http://www.westminster.edu/staff/nak/courses/BibPoetry.htm
If Paul has used "parallelism in language" in this passage, and this has been taken by some to infer poetry, then fine. Not being a poet, or a Hebrew, Greek or English scholar, I am not in any position to comment, other than to say that, for me, the linguistic beauty comes from the power of the meaning of words that inspire faith and hope in the believer.