Was the wisdom God gave to Paul kept secret before it was revealed?

Les teaches that God has seen fit to keep things secret until such time in His sovereign grace He saw fit to release and reveal it, and this applies to the whole Pauline doctrine. He points back to Deuteronomy 29:29, where Moses writes that the secret things belong unto the Lord our God, but those things which are revealed belong unto us and to our children forever. Les explains that the Old Testament knew nothing of what we call the Gospel of the grace of God, and the Gospels—Matthew, Mark, Luke, and John—knew nothing of Paul's Gospel, which went out to Jew and Gentile alike. Paul therefore uses the word over and over, saying, behold, I show you a secret or a mystery. In I Corinthians chapter 2, Les says, the wisdom God had now given to this apostle and the revelations given to this man had been kept secret, and now they are coming out into full view and into full understanding. Reading on to verse 7, we are not speaking the wisdom of the world, but the wisdom of God that has come out of a secret.