Hebrews 9:11-14

¹¹ “But when Christ appeared as a High Priest of the good things having come, He entered through the greater and more perfect tabernacle, not made by hands, that is, not of this creation; ¹² and not through the blood of goats and calves, but through His own blood, He entered the holy place once for all time, having obtained eternal redemption. ¹³ For if the blood of goats and bulls, and the ashes of a heifer sprinkling those who have been defiled, sanctify for the cleansing of the flesh, ¹⁴ how much more will the blood of Christ, who through the eternal Spirit offered Himself without blemish to God, cleanse your conscience from dead works to serve the living God?”

Once for all: The Old Covenant was based on an earthly tabernacle with insufficient sacrifices. But the New Covenant is based in a heavenly tabernacle in which Jesus offered His blood once for all for total and complete forgiveness of sin. Whereas the Old Covenant sacrifices were atoning or acted as a covering for sin, the New Covenant offered a sacrifice of propitiation that completely removed sin. The Old Covenant was merely a shadow of the reality which is the New Covenant in Christ.