How do we know that Christ has defeated sin?

The assurance of Christ's victory over sin is given in Hebrews 9:26, which affirms that He sacrificed Himself to atone for the sins of His people. This act satisfied God’s justice and freed us from the guilt and power of sin. In the Gospel, we see that the defeat of sin is complete because we are justified through faith in Christ, a truth that we must hold fast. While we still wrestle with sin in this life, we know that its ultimate power has been broken and our sins cannot condemn us before God.