THE LAW AND THE PRIESTHOOD
With the new covenant, there was a complete change of priesthood. The covenant at Sinai was initially set up incorporating the existing patriarchal priesthood with Aaron and his sons added to serve in the ministry of the High Priesthood over the nation. However, with the sin of the Golden Calf, the priesthood was changed from the firstborn tribal heads and in place of them, the Levites who had been faithful, were appointed to the priesthood (Exodus 13:2,13; 22:29; 32:25-29; Numbers 3:13; 8:17).
THE RELATION OF THE COVENANT TO THE PRIESTHOOD
Yahweh first set the covenant which He was going to make with the people before them when they arrived at Sinai, saying to them, "'Now therefore if you will obey My voice and keep My covenant, then you shall be a special treasure unto Me above all people; for all the earth is Mine. And you shall be to Me a kingdom of priests and a holy nation."" (Exodus 19:5-6a) Note, that this is before He spoke the commandments to them while they still retained the patriarchal priesthood. It was a covenant agreement based on their obedience whereupon, He would make them His "special treasure", a "kingdom of priests" and a "holy nation".
With their consent to the covenant, they were given His laws which they were to obey (Exodus 19:7-8). Yahweh God then spoke to them Himself the ten basic principles of His Law (Exodus 20:1-17). Then Moses went up the mountain to receive the remainder of the instructions for them at their request and His consent, that He not continue to speak directly to them (Exodus 19:18-21). Them Moses returned and proceeded to give them the remaining instructions which are in Chapters 20-24 of Exodus. So all the basic laws were given before the sin with the Golden Calf. This includes the Sabbath and the Feasts with other social principles. Then the offerings and furniture for the Tabernacle follow in Chs. 25-30. Notice - there is no mention of the Levitical priesthood during this time, only that of the High priest and his sons.
Yahweh's original intention was that they be a nation of priests led by the firstborn of each household and the oversight of a High priest from the lineage of Aaron. Instead they became a nation with a Priesthood.
So we see here that the priesthood with which the covenant was formed was changed when the nation sinned and broke the covenant, and the Levitical priesthood was put in place with all the rituals and ceremonies that pertained to making atonement for the sins of the nation (Leviticus 1-7). These daily offerings culminated in a final cleansing being made each year by the High Priest on the Day of Atonement (Lev.16).
With the breaking of the covenant, Moses had to make atonement for the sin of the people (Exodus 32:30-35) as well as intercede for them and renew the covenant which is outlined in Chapter 34; particularly verses 10-11, repeating the main points of the previous covenant and adding to it a promise of driving out the inhabitants of Canaan (verse 11) with an added warning against the sins of idolatry they had just committed (verses 12-17), together with an exhortation to keep His Feasts rather than the pagan forms of worship in which they had just indulged, in the worship with the Golden Calf (verses 18-26).
This was a new covenant on the same condition of obedience, "Observe what I command you this day ..." (34:11) with some changes to the benefits of the covenant, the same Law but a different priesthood. This is basically what took place with the institution of what we know as the "new covenant". There were better promises added to the covenant, but the same law with a change in the priesthood.
THE CHANGES IN THE PRIESTHOOD
The priesthood was changed from the patriarchal form of the firstborn sons representing the family in priestly service to that of one tribe performing the service for the nation at Sinai (Exodus 32:26-29; Numbers 1:47-53). Abraham functioned in this form of priestly service over his household (in which Lot was included) toward Melchizedek, the High Priest of his day (Genesis 15:18-21; 18:19, 23-32).
David, as one that rose above the system of his time, entered into the Melchizedek-type priesthood wherein he worshipped apart from the established system in a Tabernacle where he entered into the very Presence of Yahweh God, before the Ark (1 Chronicles 15:1-28). Born of the tribe of Judah, as was Yeshua his descendant, he had no right to serve as a priest after the Levitical order. But as a priest after the order of Melchizedek, he went beyond his era and established a type of the Messiah, the Lion of the tribe of Judah who would come as a High priest after the order of Melchizedek (Psalm 110:1, 4; Hebrews 5:5-6).
Sacrifices were still performed in David's tabernacle because the Messiah had not yet come, but other than that the worship was a twenty-four hour a day worship service before the earthly throne of God (1Chr.16:37-43).
He established a different form for the rituals and ceremonies for the priestly services which were incorporated into the Temple service after it was built. The law for the priesthood of the tribe of Levi was not applicable for the priesthood of the Lion of the tribe of Judah -- i.e. the Melchizedek priesthood in which he functioned.
The reversion to the Melchizedek order was not perpetuated in his son Solomon when he built the Temple, although some of it was incorporated into it. What David entered into beyond the veil was one of a kind. But it wrought a change and a progression in the Levitical priesthood to a form similar to that which will be carried forward in the Millennial Temple (Ezekiel Chs.40-46 )
THE MELCHIZEDEK PRIESTHOOD
It was the Melchizedek priesthood that was re-instated with Yeshua as our High Priest of the new Covenant, over a "kingdom of Priests" (1 Peter 2:5-9). He became the Melchizedek that was pre-figured at that time.
With the reinstatement of the Melchizedek priesthood, the covenant was also renewed back to its original form of them being a "kingdom of priests" rather than a kingdom with priests which was Yahweh's original intention for them. The proviso in the Levitical priesthood was an intermediary one, because they were stiff-necked and hard of heart (Exodus 33:5 Acts 7:51; Hebrews 3:16-19); it was never intended to be permanent.
All the form of service, the ceremonies and the rituals, pertained to the Levitical priesthood; they did not exist with the previous Melchizedek priesthood. Nor was there a physical Tabernacle in which to perform the service of priesthood in that order of priesthood. It was based upon faith in a direct personal relationship between each functioning priest and the promised Messiah whom they knew as the Word, the Son of the Father (Prov. 30:4).
And so, with the reinstatement of the Melchizedek order, the rituals and ceremonies associated with the Levitical order were not required. Nor is an earthly Temple required because we, as living stones have been made the corporate temple of the living God (1 Corinthians 3:16; 1 Peter 2:5). Also, the sacrifices we offer are spiritual sacrifices, which are our prayers and the fruit of our lips giving thanks to His Name (Ephesians 6:10-18; Hebrews 13:14-16) to our High Priest, who ever lives to make intercession for us (Hebrews 7:13-16, 23-25).
So now, we have a High Priest who is ministering in the true tabernacle erected by God of which the law pertaining to the rituals and ordinances was a but a pattern. The earthly pattern has been superseded by the reality which is taking place in heaven now by our High priest. Hebrews 8:1-2
All animal sacrifices were instituted for the atonement for sin. With Messiah offering Himself as the Lamb of God for the sin of the world, there is not only no need for the sacrifices, but there is no need for all of the requirements necessary for the priests to perform those sacrifices, as was so clearly demonstrated when the veil of the Temple was torn from top to bottom with Yeshua's perfect and complete sacrifice (Hebrews 7:27).
Now He is the mediator of a better covenant based upon better promises and a better priesthood in a better temple; that of a spiritual nature, rather than that of an earthly Sanctuary (Hebrews 8:7-13). The priesthood has been made higher and eternal by Messiah, and so the service concerning that priesthood has been made higher as well. We are all a royal priesthood now, serving in the Melchizedek order in the heavenly sanctuary.
"He has made us unto our God, a kingdom of priests, and we shall reign on the earth" (Revelation 5:10)