But Christ came as High Priest of the good things to come, with the greater and more perfect tabernacle, not made with hands, that is not of this creation. (12) Not with the blood of goats and calves, but with His own blood He entered the Most Holy Place once for all, having obtained eternal redemption. (13) For if the blood of bulls and goats and the ashes of a heifer, sprinkling the unclean,sanctifies for the purifying of the flesh, how much more shall the blood of Christ, who through the eternal Spirit offered Himself without spot to God, cleanse your conscience from dead works to serve the living God? (15) And for this reason He is the Mediator of the new covenant, by means of death, for the redemption of the transgressions under the first covenant, that those who are called may receive the promise of eternal inheritance.

The author of the letter to the Hebrews is unknown. This letter is written to Hebrew Christians, facing persecution, who were tempted to leave the Christian faith and return to Judaism which was culturally and legally protected by Rome. The author is showing them in this letter why that would be spiritually fatal.
The old covenant was inferior to the new covenant that Jesus initiated; the old covenant was temporary and imperfect in its sacrificial system dealing with the “blood of bulls and goats and the ashes of heifers” but it pointed ahead to Christ. The old system allowed only limited access to God through the High Priest and had to be repeated annually showing the incomplete nature of forgiveness. Only in Christ’s blood are the faithful provided complete access to God. In Christ it is not just a ritual but a perfect once and for all sacrifice. Christ redeems and cleanses the faithful from dead works – the focus is NOT on men but on God. Man’s works were dead because man in his human nature is spiritually dead and his works are to no avail. If eternal life could come through man’s good works then Christ died needlessly.
Jeremiah prophesied that God was going to make a new covenant with the people which would set aside the old. The first covenant was established on man’s obedience and faithfulness. The new covenant is established on God’s faithfulness through Jesus Christ. The first failed because man could not live by it but the new covenant is established forever and in Christ as our high priest our redemption is eternal. Christ became the offering itself and He was the one entering the presence of God with the offering. Christ once and for all made atonement for us: He is our mediator – our High Priest.
The message to the wavering Hebrews is clear: don’t do it.