How do we know that Jesus' sacrifice is sufficient for our sins?

In Hebrews 9:12, it is written, 'Neither by the blood of goats and calves, but by His own blood, He entered in once into the holy place, having obtained eternal redemption for us.' This verse highlights that Christ's sacrifice was not repeated like the Old Testament sacrifices; rather, it is a definitive act that secured eternal redemption. His blood is the only payment acceptable for the sins of His people—no further sacrifice is needed as His death fully fulfills the justice of God regarding sin.