I would like to comment briefly on the question, The Excellency of Speech or Wisdom. I believe a book could be written on this, but that's not my intention.

First of all, the Apostle Paul was certainly capable of excellency of speech. When we consider that he was not only a part of the Jewish world, the Roman world, a freeborn Roman citizen (Acts 22:25), and could quote the great poets, yet all of this knowledge could not do what the Gospel could do, It could only appeal and impress the carnal cravings of man.

He said in Ephesians chapter 2, verses 4 and 5, that even mysteries which had not been known in ages past were now made known; further, he says, it is through the Gospel. The wisdom of the Greeks would call a man crucified utter foolishness; to the Jew, a stumbling block, to Pilate, a real problem and a challenge to his position, his job security.

We can read any of the apostle Paul's writings and recognize his style. He followed the pattern of his Lord, he used familiar speech, plain and easy to be understood. When the Lord Jesus Christ taught, he used terms familiar to the people, things like lost sheep, lighting a candle, sweeping and looking for a lost coin, sowing and reaping. So the apostle used his manner of speaking. But it is more than that. We completely missed the mark if we tried to preach like someone else. God called Paul to preach and God blessed and used him, just as he calls us and blesses us. We must, by the grace of God, apply ourselves to the study and work of the ministry. The apostle did not try to appeal to them by excellency of speech, as was the custom of the time with the well-known poets and philosophers of the Greeks. God blessed his words with the Holy Spirit. He says it all in 1st Cor. 1:21, “...the world by wisdom knew not God, it pleased God by the foolishness of preaching (not foolish preaching) to save them that believe.”

When men turn to the wisdom of the world, and natural speech, for that matter, to try to communicate heavenly things, they are attempting an impossible task.
There are times when men receive great accolades because they use theological terms most people do not understand, and their preacher is so refined and educated he can't get down to the level of the children; so others must be used to teach them. That's not saying much for the preacher. The Lord himself taught little children.

I read a statement somewhere that said: A great sermon is not when one says what a great preacher a man is, but when one wants to be by themselves and think for a while. Anything that complicates the simplicity of the message of Christ and proclaiming Him; and that we're doing, faithfully, that which is from above, is turning to the wisdom of the world, no matter how excellent and fair the speech.