Why is the preaching of the cross foolishness to some but the power of God to others?
The preaching of the cross is foolishness to those who are perishing because salvation is God's power, not human works; no one can add to it. To those who believe and are saved, Jew first and also Greek, that same message is the power of God unto salvation.
Les teaches from 1 Corinthians 1:18 that the preaching of the cross is to them that perish foolishness, but unto us who are saved it is the power of God. He connects this with Romans 1:16, where the gospel is the power of God unto salvation to everyone that believeth, to the Jew first and also to the Greek. This leaves our works out of it: there is nothing we can do, we cannot touch it, and all we would do is tarnish it. Les illustrates this by taking the mind back to Israel coming out of Egypt under Moses. At the Red Sea they had impassable mountains on the right, populated areas to the left, the Egyptian army behind, and the Red Sea in front. They were in a dilemma. God did not say hurry up and do something, nor did He tell Moses to get out boats. Instead, He said, “Stand still. Do nothing.” That picture shows salvation is God's power rather than human effort. So the same cross message is foolishness to the perishing but power to the saved who believe.
For the preaching of the cross is to them that perish foolishness; but unto us which are saved it is the power of God.