The main idea or thought that Piper tries to convey in this chapter of the book is that there are two kinds of wisdom spoken about throughout the Bible. It is of utmost importance that we understand the difference between the two. By understanding the difference we can fight against any thoughts or ideas that promote anti-intellectualism in the christian community. Also we can distinguish between the wisdom that saves a sinner and reconciles him with God and a wisdom that is proud and will send a sinner to an eternity without God.
Paul tells us in 1 Corinthians 1:21 that the world by its wisdom can't know God. However, in 1 Corinthians 1:24 Paul tells us that the preaching of Christ crucified is " the wisdom of God."
This is the thought or idea that is covered by Piper---there are two kinds of wisdom, a wisdom from God and a wisdom of this world or a human wisdom. I'll just spend a little time on the difference between the two.
Take the time to think on this thought: Jesus told us in Luke 10:21 that God has hidden his truth form the wise, but has revealed it to the little children. Again Paul in 1 Corinthians 1:21 says that the wise of this world do not know God.
Since I like to get to the point, here it is---Piper notes that "The Cross is the continental divide between human wisdom and divine wisdom.
God's wisdom will always exalt the cross while human wisdom will always be offended by what the cross stands for.
Here is a very succinct definition given by Piper on the ultimate difference between God's wisdom and man's wisdom:
"God's wisdom makes the glory of God's grace our supreme treasure. But man's wisdom delights in seeing himself as resourceful, self-sufficient, self-determining, and not utterly dependent of God's free grace."
Thus God's wisdom promotes humility and brings us to the foot of the cross---while man's wisdom will always do things his way, man's wisdom will not submit to God's plan. All of the religions of this world are built on man's wisdom, and only Christianity is built on the wisdom of God, where the cross is lifted up and exalted.
Take the time to read 1 Corinthians 1:1-3 and see how these two types of wisdom are contrasted.