On the opening of 1 Corinthians (1 Corinthians 1.10-4.21) by Paul Ellis …
“Paul’s argumentation in [1 Cor.] 1.10-4.21 is arranged in chiastic form, i.e., he begins with a general treatment of his problem; … then he moves on to what appears to be a digression; … and he concludes by returning to the themes of 1.10-2.5, giving practical solutions and advice … It is the same A-B-A format Paul used in 1 Thessalonians. He will use it regularly throughout 1 Corinthians …”
“… the parallel structure of 1.10-4.21 … is perhaps the most elaborate use of parallelism in all of the Pauline epistles.”
Source: Seven Pauline Letters by Peter F. Ellis (The Liturgical Press, 1982); pp.47-48.