What does the preaching of the cross become to those who are saved?

Les explains that the preaching of the cross is foolishness to them that perish—those who reject, ridicule, and scorn it—because they question what something 2,000 years ago has to do with them today. But unto us who are saved and have believed it, that preaching becomes the power of God, a word he wants underlined. He illustrates this power by saying that just as God opened the Red Sea by His power, God also exercises His power not only in resurrecting Christ from the dead but in bringing us out of our deadness in sin and slavery to it. Les then points to verse 24: unto them who are called, both Jews and Greeks, Christ is the power of God and the wisdom of God, so we have to rely upon that power.