How do we know that Christ's sacrifice obtained eternal redemption?

In Hebrews 9:12, we see the pivotal truth that Christ, as our High Priest, entered the holy place once for all with His own blood, thereby obtaining eternal redemption. Unlike the Levitical priests who repeatedly offered sacrifices, Christ's death was a one-time event that satisfied divine justice on behalf of His people. This unique sacrifice not only secured forgiveness for sins but also established an eternal covenant, proving that His redemption is everlasting. By believing in Him, believers are assured that they have been redeemed from sin and will never be lost, as He Himself affirmed that nothing can snatch them out of His hand.