A.T. Robertson Commentary 1 Corinthians 2:4

"And my speech and my preaching were not in persuasive words of wisdom, but in demonstration of the Spirit and of power:" — 1 Corinthians 2:4 (ASV)

Not in persuasive words of wisdom (ουκ εν πιθοις σοφιας λογοις). This looks like a false disclaimer or mock modesty, for surely the preacher desires to be persuasive. This adjective πιθος (MSS. πειθος) has not yet been found elsewhere. It seems to be formed directly from πειθω, to persuade, as φειδος (φιδος) is from φειδομα, to spare. The old Greek form πιθανος is common enough and is used by Josephus (Ant. VIII. 9. 1) of "the plausible words of the lying prophet" in 1Ki 13. The kindred word πιθανολογια occurs in Col 2:4 for the specious and plausible Gnostic philosophers. And gullible people are easy marks for these plausible pulpiteers. Corinth put a premium on the veneer of false rhetoric and thin thinking.

But in demonstration (αλλ' εν αποδειξε). In contrast with the

plausibility just mentioned. This word, though an old one from αποδεικνυμ, to show forth, occurs nowhere else in the New Testament.

Spirit (πνευμα) here can be the Holy Spirit or inward spirit as opposed to superficial expression and

power (δυναμις) is moral power rather than intellectual acuteness (cf. 1:18).