I Corinthians 2:5

Holy men of God spake as they were moved by the Holy Ghost.—That which we have seen and heard declare we unto you, that ye also may have fellowship with us: and truly our fellowship is with the Father, and with his Son Jesus Christ.

Behold my hands and my feet, that it is I myself: handle me, and see; for a spirit hath not flesh and bones, as ye see me have. And when he had thus spoken, he shewed them his hands and his feet.—He that saw it bare record, and his record is true: and he knoweth that he saith true, that ye might believe.

Behold, are not all these which speak Galilaeans?

Jesus, . . . saw two brethren, . . . casting a net into the sea: for they were fishers. And he saith unto them, Follow me.

I believed not the words, until I came, and mine eyes had seen it; and, behold, the half was not told me.

The queen of the south shall rise up in the judgment with this generation, and shall condemn it: for she came from the uttermost parts of the earth to hear the wisdom of Solomon; and, behold, a greater than Solomon is here.

Paul was a scholar and an orator of the first rank; he is not speaking out of abject humility; but saying that he would veil the power of God if, when he preached the gospel, he impressed people with his "excellency of speech."

Belief in Jesus is a miracle produced only by the efficacy of Redemption, not by impressiveness of speech, not by wooing and winning, but by the sheer unaided power of God.