It’s interesting that the word boast in this verse can also be translated “exult in” or “rejoice in”. So Paul is saying, “I don’t want to rejoice in anything except the cross.” We rejoice in several things on any given day. But how much in any given day do we rejoice in the cross? There are several reasons that the cross brings rejoicing in our life.

1. The cross has power to free us.
Specifically, he talks about the world. This isn’t the physical world in which we live, but the cultural world that is opposed to God. The liberating power of the cross frees me from this passing age which is opposed to God. I am dead to the world and the world is dead to me through the cross.
The cross of our Lord Jesus Christ frees us from the power of sin. “Christ appeared so that he might take away our sins” (1 John 3:5).
The cross can free me from my guilt. “Therefore there is now no condemnation for those who are in Christ Jesus. Because through Christ the law of the spirit of life has set me free from the law of sin and death.” (Romans 8:1-2).

2. The cross has power to bless me.
Rom. 8:31-32 – if God is for us who can be against us? He who did not spare his own son, but gave him up for us all – how will he not also, along with him, graciously give us all things? Whatever I need pales in comparison to what God has already given me in Jesus Christ!
I rejoice in the cross because I know God has already blessed me with the greatest gift so I can trust him to bless me with lesser gifts.

3. The cross has power to give me victory.
Specifically in two areas. Victory over the devil and death.
“The reason the Son of God appeared was to destroy the works of the devil.” (1 John 3:8).
In 1 Corinthians 15: 55-58 we read about our victory over death. “Where o death is your victory? Where, o death, is your sting? The sting of death is sin, and the power of sin is the law. But thanks be to God he gives us the victory through our Lord Jesus Christ. Therefore, stand firm. Let nothing move you. Always give yourself fully to the work of the Lord, because you know your labor is not in vain.” Stand firm in this victory. Don’t let anything move you away from this victory. Give yourself fully to God’s work.
Victory in Christ is something to rejoice about.

4. The cross has power to give me hope.
Romans 8:11 – “If the Spirit of him who raised Jesus from the dead is living in you, he who raised Christ from the dead will also give life to your mortal bodies through his spirit who lives in you.” That’s hope! That’s certain! Without Christ’s death, there is no resurrection. Without a resurrection we have no hope.

But the main reason I rejoice in the cross, is because it shows me how much God loves me.
“This is love: not that we loved God, but that he loved us and sent his Son as an atoning sacrifice for our sins.” 1 John 4:10
We can rejoice about several things in any given day, but nothing compares to the rejoicing we have in the cross of Christ Jesus our Lord.