Read 1 Corinthians 2.
Paul was highly educated, intellectually capable, multi-lingual, and a trained debater. To the more experienced in the faith, Paul communicated insights into the Scriptures and the "wisdom of God" (vv.6-7). But when he taught in public, he kept it simple. The message centered on the implications of "Jesus Christ and him crucified" (v.2). His ministry was even accompanied by the "demonstration of the Spirit and of power." Lives were being transformed. People experienced forgiveness of sin and the freedom of a clean conscience. Some behaviors changed. What took place was undeniable!
Even though the message of Jesus was so simple a child could respond in faith, and though the power of God was evident, still many did not get it.
"None of the rulers of this age understood." (v.8)
"No one comprehends..." (v.11)
"He is not able to understand..." (v.14)
And, the question is why?
Everyone has family members, dear friends, neighbors and acquaintances who do not know Jesus as their Savior. It is a heartache the believer carries daily in prayer. Why don't they understand the urgency and the loving kindness of God?
The truth about God and His word can never be fully understood by natural means. Jesus said, "God is spirit, and those who worship him must worship in spirit and in truth." (John 4:24). In other words, eyes, ears and intellect will prove useless in fully comprehending spiritual truth and spiritual things. Because it is spiritual and not natural, one must have the help of the Holy Spirit to understand and appreciate the wonderful work of Christ and His offer of salvation by grace. To the natural person these things may sound foolish and optional.
This is clearly explained in verses 9 and 10. Often only verse 9 is quoted and misapplied regarding some future plans of God. However, the rest of the sentence continues in verse 10 by saying "these things God has revealed to us through the Spirit." Notice the verb tense. Those who personally know Jesus already have the indwelling Holy Spirit alongside to help them. Understanding and obeying God's word is evidence of what Paul called having "the mind of Christ" (v.16).
Even the number one Rabbi in Jesus' day did not understand this. In John 3, Jesus compared it to a birth. A physical birth alone will not result in a relationship with God and eternal life. "That which is born of the flesh is flesh, and that which is born of Spirit is spirit. Do not marvel that I said to you, 'You must be born again.'" When one is born into God's family through faith in Jesus, the Holy Spirit then does a work of unlocking our human understanding.