What does 1 Corinthians 1:18 mean?

Paul now begins to expand on his statement from the end of verse 17: that Christ did not send him to focus on words of eloquent wisdom as he preached the gospel, lest the cross of Christ be emptied of its power. Paul divides the world into two groups of people: those who are perishing and those who are being saved. Those perishing are destined for eternity apart from God, while those being saved are destined for an eternity of sharing in God's glory.

To the first group—the perishing—the cross of Christ is "folly." The original Greek term used here is mōria, from the same root word forming English words such as moron. In blunt terms, Paul is saying that to the unsaved world, those who preach the gospel look like idiots. Broadly speaking, ungodly people think believers, and their faith, are stupid.

In Paul's day, the cross remained in widespread use by the Romans as a means of public execution. It was a symbol of shameful crimes and powerlessness before the irresistible Roman empire. The cross of Christ was not foolish in the Greek and Roman culture as a result of atheism. In truth, they believed in all kinds of gods and sorted them by the power they wielded over nature and humanity. The cross of Christ was foolish to the pagan culture because Jesus Christ was rejected by His own people and crucified like any other common criminal by the Roman machine.

From the Greek and Roman perspective, that was no kind of god to worship.

For those who are being saved, because of their faith in Christ, the cross is understood to be God's most powerful act. God's Son did not lose a fight with the Jewish leaders or the Roman government. He wasn't overpowered or outmatched (John 10:17–18; 18:6; Matthew 26:53). God the Father sacrificed His Son Jesus for human sin. Jesus, in spite of limitless power and authority, gave up His life to cover the sins of those who were perishing.

Those who trust in Christ understand that without that powerful act, we would be lost and without hope.