I used the book These Are The Garments by C. W. Slemming to aid in this study.
The Priestly position seems to be a progression thru Genesis. Abraham performed the duties of a priest, then Moses said it should be through a chosen person and he set up the rules that God showed him.
First, a priest was called. Aaron didn't volunteer. God selected him specifically for this task. Hebrews 5:4- And no man taketh this honour unto himself, but he that is called of God, as was Aaron.
Christ was also called by God for this task. Hebrews 5:5-6- So also Christ glorified not himself to be made an high priest; but he that said unto him, Thou art my Son, to day have I begotten thee. As he saith also in another place, Thou art a priest for ever after the order of Melchisedec.
So, we see that the calling took place by God upon a chosen man. The same is true today of those who minister to God (Ephesians 4:1-2).
Next, a priest was cleansed. In Exodus 29:4- And Aaron and his sons thou shalt bring unto the door of the tabernacle of the congregation, and shalt wash them with water.
Christ was also cleansed with water when he was baptized by John the Baptist.
Salvation is through the blood, not water. This cleansing doesn't signify salvation (which a man would have before being called). This cleansing is getting into the Word of God (John 15:3; Psalms 119:9).
Following the cleansing, the priest was then clothed in the special garments that God himself designed. Exodus 29:5-6- And thou shalt take the garments, and put upon Aaron the coat, and the robe of the ephod, and the ephod, and the breastplate, and gird him with the curious girdle of the ephod: And thou shalt put the mitre upon his head, and put the holy crown upon the mitre. These clothes were unique in that there were none like them on the earth. No one else was able to wear these clothes except he whom God had called and he who had been cleansed.
Christ was also clothed with a unique spirit. The Holy Spirit in Matthew 3:16- And Jesus, when he was baptized, went up straightway out of the water: and, lo, the heavens were opened unto him, and he saw the Spirit of God descending like a dove, and lighting upon him: It is unique in that it stayed with him and didn't leave like did to people in the Old Testament. John 1:33- And I knew him not: but he that sent me to baptize with water, the same said unto me, Upon whom thou shalt see the Spirit descending, and remaining on him, the same is he which baptizeth with the Holy Ghost.
We, today, are given this blessed seal when we are saved by the blood of the Lord Jesus Christ (Ephesians 1:13).
The consecration now lay upon these men, Exodus 29:9- And thou shalt gird them with girdles, Aaron and his sons, and put the bonnets on them: and the priest's office shall be theirs for a perpetual statute: and thou shalt consecrate Aaron and his sons. The consecration goes on until verse 36. They kill a ram and put it's blood on their right ear, right thumb, and right big toe. I don't understand this, but Slemming theorizes that it was on the ear so they might be sensitive to the law of God and they might hear the confessions of the people's sin. The thumb that they might do the bidding of God and handle the offerings of the people. And the great toe that they might walk in the ways of God and minister for God and not gain.
Christ was consecrated when he was clothed with the Holy Spirit. And confirmed by God in the next verse- Matthew 3:17- And lo a voice from heaven, saying, This is my beloved Son, in whom I am well pleased.
Consecration of a Christian is something that Slemmer doesn't really delve into. I, personally, believe that it's a daily thing that we choose to do. We are consecrated when we walk according to His will and not according to the desires of our heart. When we allow him to take over "my life" and live according to "not my will, but thine be done" (Romans 12:1-2).
A priest must be compassionate. This is a common sense thing, but knowing that all priests are men we understand that their compassion would be based upon their feelings. Could they relate? Were they able to weep with those who weep?
Christ is the only truly compassionate priest. Whereas all others would change their feelings on a daily basis, His would be consistent. Hebrews 4:15- For we have not an high priest which cannot be touched with the feeling of our infirmities; but was in all points tempted like as we are, yet without sin.
And lastly, the priest was commissioned. They had to obey the instructions of God to become intercessors for the people they killed the sacrifices for. It was a very specific process. Each sin had a specific sacrifice that had to killed in a specific manner.
Christ was commissioned to be the mediator between God and man. I Timothy 2:15- For there is one God, and one mediator between God and men, the man Christ Jesus; This commission had have a specific sacrifice killed in a specific was. Hebrews 9:12-14- Neither by the blood of goats and calves, but by his own blood he entered in once into the holy place, having obtained eternal redemption for us. For if the blood of bulls and of goats, and the ashes of an heifer sprinkling the unclean, sanctifieth to the purifying of the flesh: How much more shall the blood of Christ, who through the eternal Spirit offered himself without spot to God, purge your conscience from dead works to serve the living God?
The only difference is that Christ only had to offer His sacrifice once! Hebrews 10:11-12, 14- And every priest standeth daily ministering and offering oftentimes the same sacrifices, which can never take away sins: But this man, after he had offered one sacrifice for sins for ever, sat down on the right hand of God; For by one offering he hath perfected for ever them that are sanctified. Hebrews 9:28- So Christ was once offered to bear the sins of many; and unto them that look for him shall he appear the second time without sin unto salvation.
Christ is called a priest after the order of Melchisidec. We read about Melchisidec in Genesis 14:18-20 and again in Hebrews 7:1-3.
The Levitical priests were chosen by their family. The sons inherited the position from their fathers. If you weren't born in the tribe of Levi and you weren't of the lineage of Aaron, we couldn't assume the position of the priest.
The exception to this rule in the Old Testament was Melchisidec. Genesis 14:18-20- And Melchizedek king of Salem brought forth bread and wine: and he was the priest of the most high God. And he blessed him, and said, Blessed be Abram of the most high God, possessor of heaven and earth: And blessed be the most high God, which hath delivered thine enemies into thy hand. And he gave him tithes of all. Melchisidec was a King and a priest.
The kingly line went thru Judah. Hence, no king could be a priest! Priests came from Levi, and Kings came from Judah!
Hebrews 7:1-3- For this Melchisedec, king of Salem, priest of the most high God, who met Abraham returning from the slaughter of the kings, and blessed him; To whom also Abraham gave a tenth part of all; first being by interpretation King of righteousness, and after that also King of Salem, which is, King of peace; Without father, without mother, without descent, having neither beginning of days, nor end of life; but made like unto the Son of God; abideth a priest continually.
These verses seem to say that Melchisidec was a supernatural person. He was not! He was human being who served the Most High God as a King and a Priest.
Salem is present day Jerusalem. Melchisidec was the King of peace (Salem interpreted), the King of the ancient Jerusalem. He was also a priest.
From whom did he inherit his priesthood? The Bible tells us it wasn't from his father or his mother. Remember, Jews inherited it from their lineage and tribe! To whom did he pass it on? The Bible doesn't say. As far as we know he was the only King to hold this position as Priest, a unique individual with a unique calling.
Christ is called after the order of Melchisidec. He is of the tribe of Judah- in line for the throne. He can, by lineage, become the King of Jerusalem. He, by death, became the King of Peace- making peace between our sins and a Holy God! And he also, by special calling, became a priest- just like the unique calling of Melchisidec. He didn't inherit it from his father or his mother, and he won't be passing it on to anyone either.
He is the one and only Great High Priest. He supersedes all others because he is ever living and ever able to make intercession for all! Hebrews 7:25- Wherefore he is able also to save them to the uttermost that come unto God by him, seeing he ever liveth to make intercession for them.