Paul speaks in 1st Corinthians about God’s secret wisdom. And what is that secret wisdom? It’s none other then Jesus Christ, who was destined for our glory before time began.
The secret of God’s wisdom is that in Christ, all of humanity is freely offered relationship with God. Just as in Adam, all have sinned. Just as all nations came from the seed of Adam, all nations and sinned against God and each other: Men, women and children, are freely invited to have relationship with God, the forgiveness of sins, and receive the empowering presence of the Holy Spirit.
This then is God’s secret wisdom, unveiled for all, to plainly see.