Why was God's secret among the Gentiles something that had never been heard of before?
It was unprecedented because God had dealt with Israel for over 2,000 years before Christ. The mystery that Christ is in Gentiles, giving them the hope of glory, was not revealed in the Old Testament or Gospels, but only in Paul's epistles.
Les explains that in Colossians 1:27 Paul writes of the riches of the glory of this mystery among the Gentiles. Such a statement is not found in the four Gospels, the Old Testament, or any other part of the Bible except Paul's epistles. God had been dealing with Israel for over 2,000 years before Christ came, but now He was dealing with Gentiles, which had never been heard of before. This secret is part of the overall body of truth called the mysteries, and this particular one is that Christ is in you, the hope of glory. Les then connects this to Romans 8:10, where if Christ be in you, the body is dead because of sin. The old Adam, the flesh, is under the curse, and this body will die unless the Lord comes to translate us; it is all part of the fall of man, in which death came in and all men have to die.
To whom God would make known what is the riches of the glory of this mystery among the Gentiles; which is Christ in you, the hope of glory:
More Questions
What is the mystery among the Gentiles that Paul says God made known?
The mystery, or secret, revealed among the Gentiles is that Christ is in you, and it is one part of the larger body of truth Paul calls the mysteries.
Which mystery is Paul referring to when he speaks of the secret among the Gentiles?
The secret concerning the Gentiles is part of the overall body of truth called the mysteries, and this particular mystery is that Christ is in you.