Exodus 29:1

Exodus 29:1 says, And this is the thing that thou shalt do unto them to hallow them, to minister unto me in the priest’s office: Take one young bullock, and two rams without blemish,   Aaron and his sons didn't just decide that they would be priests.  God chose them to be priests, and then they were hallowed, or consecrated as priests.  We today, when we become followers of Christ, become a part of the priesthood of believers, not because we choose to be, but because God calls us to be.  Then, whatever function we have in the church, it is because God calls us to that function.  

Verse two adds, And unleavened bread, and cakes unleavened tempered with oil, and wafers unleavened anointed with oil: of wheaten flour shalt thou make them.  In addition to the young bullock and two rams without blemish mentioned above, they were to take unleavened bread and cakes tempered with oil, and wafers anointed with oil.  

Verse three continues, And thou shalt put them into one basket, and bring them in the basket, with the bullock and the two rams. consecrate them, and sanctify them, that they may minister unto me in the priest’s office.  All the bread was to be put in one basket, and brought with the bullocks and two rams to consecrate and sanctify Aaron and his sons so that they might minister as priests.   When we come to God today to join the priesthood of believers, we must come by being sanctified by our faith in Christ, Who was our sacrifice for our sins.  

Verse four states, And Aaron and his sons thou shalt bring unto the door of the tabernacle of the congregation, and shalt wash them with water.  Aaron and his sons were to be brought into the tabernacle and washed with water.  

Verse five adds, 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:  Aaron was to be dressed in the priestly garments of the High priest.  We today as followers of Christ are dressed in the righteous of Christ.  Though we do not have physical garments to set us aside, we are nonetheless washed by the blood of Christ and covered by His righteousness.  

Verse six continues, And thou shalt put the mitre upon his head, and put the holy crown upon the mitre.  The mitre was to be placed on Aaron's head.  

Verse seven says, Then shalt thou take the anointing oil, and pour it upon his head, and anoint him.  Aaron was to be anointed with oil, signifying that he was consecrated to God.  

Verse eight adds, And thou shalt bring his sons, and put coats upon them. 

Verse nine continues, 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.  Aaron's sons were then to be dressed in the coats of the priesthood, and all were to have on girdles and bonnets.  They were basically to be covered from head to toe in priestly garments, just as we are to be completely covered by the righteousness of Christ today.  The priesthood was to be theirs for a perceptual state, just as our priesthood as believers today is perpetual, if we are consecrated by the blood of Christ.