The word translated "preaching" in verse 18 of the KJV is λόγος which does not refer to the method of delivery but rather the content.
1Co 1:18 For the message about the cross is nonsense to those who are
being destroyed, but it is God's power to us who are being saved.
In this context then, λόγος is referring to the "message" which is "inadequately sophisticated" for Greek sophism and rhetorical taste.
BDAG provides a single gloss for μωρία and that is highlighted below:
μωρία, ας, ἡ (μωρός; Soph., Hdt. et al.; PBrem 61, 28 [II A.D.];
PCairMasp 4, 6 Byz.; Sir 20:31; 41:15; Philo; Jos., Ant. 17, 209;
Iren. 1, 16, 3 [Harv. I, 162, 2]) foolishness gener. of worldly
wisdom (Orig., C. Cels. 7, 47, 9) μ. παρὰ τῷ θεῷ ἐστιν 1 Cor 3:19.
Conversely, to all those who are lost 1:18 and esp. to the gentiles
vs. 23, the Christian preaching of a Savior who died a slave’s death
on the cross was μ. (cp. Theoph. Ant. 2, 1 [p. 94, 7]). It has pleased
God to save the believers διὰ τ. μωρίας τοῦ κηρύγματος vs. 21. The
ψυχικὸς ἄνθρ. rejects the things of the spirit as μ., 2:14. The Judean
temple cult is evaluated as μ. (opp. θεοσέβεια) Dg 3:3.—WCaspari, Über
d. bibl. Begriff der Torheit: NKZ 39, 1928, 668–95.—DELG s.v. 1
μωρός. TW. Spicq.
Arndt, W., Danker, F. W., & Bauer, W. (2000). A Greek-English lexicon
of the New Testament and other early Christian literature (3rd ed., p.
663). Chicago: University of Chicago Press.
So the word is generally translated "foolishness". However, in the current context Paul's preaching is not said to be "foolishness" but rather that it is viewed that way by people who measure a message by its conformity to popular notions of "scholarship" and "academic style" (such standards recently being an issue on this site).
So the enemies of Paul attack his preaching for its lack of craft and sophistication. In other words, they "down vote" Paul's preaching because it isn't framed in the trappings of Greek scholarship. But Paul defends his preaching saying that the proper measurement of his proclamation is not how styled his preaching is in regards to "sophistication of wording" but rather on effectiveness. Paul says God likes that his message is outside of the comfort zone of the scholars because he has a plan in using such a crude message:
- he puts a stumbling-block in front of the sophists, for which God has contempt
- he puts the message in easy reach of the simple
So Paul is saying that the message of God is not insufficiently rhetorically developed but rather it is intentionally deceptively simple so that it can only be valued by those who seek God and is of no appeal to others:
Mat_11:25 At that time Jesus answered and said, I thank thee, O
Father, Lord of heaven and earth, because thou hast hid these things
from the wise and prudent, and hast revealed them unto babes.
Luk_10:21 In that hour Jesus rejoiced in spirit, and said, I thank
thee, O Father, Lord of heaven and earth, that thou hast hid these
things from the wise and prudent, and hast revealed them unto babes:
even so, Father; for so it seemed good in thy sight.