From First Corinthians by George T. Montague, SM, commenting on I Corinthians 2:6-10
Paul insists on the basic and incompatible difference of this wisdom from a wisdom of this age and that of the rulers of this age. In the light of verse 8, the rulers of this age are those who crucified Jesus, the leaders of both the Jews and the pagans, conceived here as instruments of Satan, the “prince of this world” (John 12:31 NIV). Worldly wisdom, in the light of what God has done, has proved itself bankrupt.
This explains the emphatic position of the word “God” in the next verse—God’s wisdom, not man’s, is what we speak. And God’s wisdom is now no longer to be read merely in the open book of creation; his mysterious wisdom has now become accessible. The word “mystery,” derived from a word meaning “to close,” particularly in the sense of closing the lips, means something secret, or as our text specifies, hidden. This wisdom, as Chrysostom observed, is called a mystery and hidden not because it is now secret but because it can be known only by the revelation God has made (Luke 8:10; Col 1:26–27), because it is attainable only through faith and is beyond all expectation (1 Cor 15:51).
Paul uses mysterion not in the Greek sense, in which the mystery is attainable only by the select few, but in the Jewish sense, in which the mystery is God’s plan for his people, his secret counsel, to which the prophets are given access and which they communicate to his people. In calling Christ the mystery, Paul gives the word a meaning far removed from Greek esoteric practice, for it is something to be shared with the entire world. Yet as Chrysostom likewise observed, “Though everywhere preached, it is still a mystery,” for it exceeds the dimensions of human thought.
Hence Paul will later describe the mystery in terms of richness and plenitude, as the source of endless growth in knowledge on the part of the believer (Eph 3:18–19; Col 1:26–27; 2:2–3). To speak this wisdom is to share a Spirit-inspired insight into the faith, something of which every faith-filled Christian should be capable.