Why Are Some Utterances of Paul "Hard to Understand"?

Paul's letters can often be difficult to understand (in Greek or English). The apostle was a profound thinker, a point that I think is borne out by looking at the illustrations he uses (1 Corinthians 15:35-49). Granted, he was writing under inspiration and by means of the wisdom that God gave him (2 Peter 3:15); nevertheless, the Bible allows human personalities and abilities to shine through the text too (1 Corinthians 7:12, 39-40).

But it is not always easy to follow Paul's involved line of reasoning (Romans 9:15-33; Gal 3:1-20). Why is he hard to understand at times (2 Pet 3:15-16)?

A.T. Robertson makes this observation:

"The style of Paul, like his theology, has challenged the attention of the greatest minds. Farrar calls his language 'the style of genius, if not the genius of style.' There is no doubt about its individuality" (A Grammar of the Greek NT, p. 128).

Robertson also mentions K.L. Bauer, who compares Paul's writings to the treatises written by the ancient Greek historian Thucydides. And here is what one scholar (John H. Finley, Jr.) has to say about the historiographical style of Thucydides:

"At farthest remove from the nascent [earliest Greek] prose is the co-called periodic style of Plato, Isocrates and the writers of the fourth century generally. By studious subordination of minor points to the major idea of a sentence, it achieves impressive organic unity but commonly at the cost of sapping the vitality of subordinate ideas. This is the style, which, adopted from Isocrates by Cicero, passed from him into the English cadences of Gibbon and Burke. Thucydides' prose stands somewhere between these two, the simple and periodic, styles. His chief devices are antithesis, comparison and contrast. Within any given sentence, clause will be paired with clause, subject with subject, verb with verb. This elaborately antithetical method is more characteristic, to be sure, of the speeches than of the common narrative" (The Peloponnesian War, page x in the introduction).

With the foregoing in mind, read (in Greek) Ephesians 1:3-14; Rom 1:24-28; 5:12-21; Galatians 5:19-21.

In addition to these points, it is important to remember that Paul employs numerous literary or rhetorical devices. His letters have even been compared to apologetico-rhetorical treatises of antiquity, although there may be some legitimate differences between the Pauline letters and epistles penned in the ancient world.

Timothy George (see his commentary concerning Galatians) makes an interesting point regarding the Pauline letters when he points out that H.D. Betz outlines Galatians as follows:

Exordium: Gal 1:6-11

Narratio: Gal 1:12-2:!4

Propositio: Gal 2:15-21

Probatio: Gal 3:1-4:31

Paraenesis: Gal 5:1-6:10

Postscript: Gal 6:11-18.

While George believes this analysis has some advantages, he thinks "Betz seems to have gone too far in pressing Galatians into the rhetorical structure of apologetic letters" (Galatians, page 64).

This caveat should be duly noted, but I also concur with Betz in some respects. I have worked with a number of Latin and Greek apologetico-rhetorical treatises (Tertullian, Lactantius, Cyprian, Tatian, Quintillian) as well as literary devices/tropes in general. The Apostle Paul is a master rhetor, as far as I can tell, even if he appears to speak of rhetoric in pejorative terms at times and possibly did not have formal training.