Whenever the priests of Israel would approach their duties for making sacrifice, they were careful to wear the right clothes. Exodus 28 describes the priestly garments to be warn as the priests took on a mediating role for Israel. The Israelite priests had their own need to make sacrifice for their own sins. They had to ensure that they were a picture of a pure Mediator who could take on this role between God and man in making sacrifice for sin. They had mediating roles for God's people and wore robes and breastplates with stones inset in them to signify the twelve tribes of Israel. They had a mediating role for God's people. Everything was to be beautiful and clean as they approached their work.
If you read through Exodus 28, you come to an unexpected importance for the clothes of the priesthood. Exodus 28:42-43 You shall make for them linen undergarments to cover their naked flesh. They shall reach from the hips to the thighs; 43 and they shall be on Aaron and on his sons when they go into the tent of meeting or when they come near the altar to minister in the Holy Place, lest they bear guilt and die. This shall be a statute forever for him and for his offspring after him.
The law for the priesthood states that if they don't wear it, they will bear guilt and die. Why should it be so important that this undergarment be mentioned with such priority? The answer has us looking back to Genesis 2 and 3. In the last verse of Genesis 2, Adam and Eve in their pre-sin condition were naked and unashamed. It was not until sin came into the world (Genesis 3), that Adam and Eve realized their nakedness in the shameful reality of their sin. Nakedness is a depiction of the guilt and shame of sin. The priests were not to expose nakedness in their mediating role.
There is another place in the Scriptures where we are surprised to see detail and priority given to the consideration of undergarments. John 19:23-24 When the soldiers had crucified Jesus, they took his garments and divided them into four parts, one part for each soldier; also his tunic. But the tunic was seamless, woven in one piece from top to bottom, 24 so they said to one another, "Let us not tear it, but cast lots for it to see whose it shall be." This was to fulfill the Scripture which says, "They divided my garments among them, and for my clothing they cast lots." So the soldiers did these things.
Jesus came to the cross in the clothes he was wearing but they were taken and given to the soldiers. Specific mention is made of his tunic (his undergarment) which was woven in one piece from top to bottom. This is the same description given for the undergarments of the priesthood. The difference here is jaw-dropping. The priests must not expose their nakedness in their mediating role lest they bear their own guilt. Jesus, who was without guilt, was stripped of his undergarment and in the exposure of his body on the cross was openly bearing the guilt and shame of humanity placed on him.
This is yet another revelation of Jesus as our Great High Priest. He who had no sin of his own was stripped bare to expose the shame and guilt of humanity as he bore our sin on the cross. He is the one true Mediator between God and man.
Humanity has no way of covering our sin. Far from trying to expose nakedness, people attempt to clothe themselves in their own good works hoping that God will see them covered in goodness. The prophet Isaiah warned us of the futility of this exercise. Isaiah 64:6 We have all become like one who is unclean, and all our righteous deeds are like a polluted garment. We all fade like a leaf, and our iniquities, like the wind, take us away. Our good works can only cover us in putrid sin.
While our shame and guilt are exposed and crucified with Jesus, through faith in him we are covered with the one thing we need most and can never obtain - righteousness. Jesus has taken our shame and clothed us with his righteousness.
And because of Jesus... one day we will live eternally without shame. When we put on the High Priestly Garment, we are putting on the righteousness of Christ.