How do we know Jesus' sacrifice is sufficient for atonement?

The sufficiency of Christ's sacrifice for atonement is grounded in the fulfillment of the Old Testament sacrificial system. Hebrews 9:12 states that Christ entered the holy place once for all, not by the blood of goats and calves, but by His own blood, having obtained eternal redemption. This signifies that unlike the repeated animal sacrifices that could only temporarily cover sins, Christ's one-time offering effectively purges the conscience and secures salvation for His people. His substitutionary death satisfies God's justice and, through His blood, believers are justified and reconciled to God, illustrating that His sacrificial work is wholly sufficient for atonement.