How do we know Christ's sacrifice for our sin is sufficient?

The sufficiency of Christ's sacrifice lies in its complete nature, where one act of sacrifice addresses all sin for those He represents. The apostle Paul expresses this in Galatians 6:14, where glorying in the cross signifies recognizing that it is through Christ's death that believers are freed from condemnation. It's an act that does not require supplementary human effort; His blood is enough. This assurance of salvation gives believers peace, effectually communicating the gravity and adequacy of what Christ accomplished on the cross for their sins.