For every high priest chosen from among men is appointed to act on behalf of men in relation to God, to offer gifts and sacrifices for sins. He can deal gently with the ignorant and wayward, since he himself is beset with weakness. Because of this he is obligated to offer sacrifice for his own sins just as he does for those of the people. And no one takes this honor for himself, but only when called by God, just as Aaron was. So also Christ did not exalt himself to be made a high priest, but was appointed by him who said to him, “You are my Son, today I have begotten you”; as he says also in another place, “You are a priest forever, after the order of Melchizedek.”
In the days of his flesh, Jesus offered up prayers and supplications, with loud cries and tears, to him who was able to save him from death, and he was heard because of his reverence. Although he was a son, he learned obedience through what he suffered. And being made perfect, he became the source of eternal salvation to all who obey him, being designated by God a high priest after the order of Melchizedek. – Hebrews 5:1-10 ESV
In the early days of Israel, the high priest was an appointed position. Aaron was the original high priest, designated so by God Himself. His command to Moses to set aside Aaron and his sons as priest is recorded in Exodus 28:1: “Then bring near to you Aaron your brother, and his sons with him, from among the people of Israel, to serve me as priests—Aaron and Aaron’s sons, Nadab and Abihu, Eleazar and Ithamar.” God would later qualify the vital nature of their calling. “I will consecrate the tent of meeting and the altar. Aaron also and his sons I will consecrate to serve me as priests. I will dwell among the people of Israel and will be their God. And they shall know that I am the Lord their God, who brought them out of the land of Egypt that I might dwell among them. I am the Lord their God” (Exodus 29:44-46 ESV). Aaron and his sons were set apart by God to serve as priests, offering sacrifices on behalf of the people. No one else could serve in this capacity. King Saul attempted to do so, and lost his kingship because of it. During the days of Israel’s wilderness wandering, Korah, a Levite, incited a rebellion against Moses and Aaron, demanding that he and his brothers be made priests. But Moses told him, “would you seek the priesthood also? Therefore it is against the Lord that you and all your company have gathered. What is Aaron that you grumble against him?” (Numbers 16:10-11 ESV). As a result of their attempt to self-appoint themselves as priests, Korah, Dothan, Abiram and all their families were literally swallowed alive by the earth. The priesthood was a serious matter to God. And so when we read of Jesus being appointed high priest “to act on behalf of men in relation to God” it should get our attention. Jesus was not a descendant of Aaron. He was a descendant of David, from the tribe of Judah. Technically, He was not qualified to be a priest, let alone the high priest. And the writer of Hebrews makes it perfectly clear that Jesus “did not exalt himself to be made high priest, but was appointed by him [God]” (Hebrews 5:5 ESV). So unlike Korah, Jesus was not guilty of trying to anoint Himself high priest. He, like Aaron, was chosen by God to serve in this capacity.
But Jesus was of a different priesthood than that of Aaron. He was “designated by God a high priest after the order of Melchizedek” (Hebrews 5:10 ESV). Melchizedek was an obscure figure mentioned in Genesis 14. Abraham had rescued Lot and his family, who had been taken captive when the cities of Sodom and Gomorrah had been overrun by an alliance of kings. After having defeated the kings and taken back Lot, his family and all their possessions, Abraham was met by Melchizedek, king of Salem. The text tells us that Melchizedek was also a priest of God Most High. Melchizedek blessed Abraham and Abraham gave Melchizedek a tenth of all the plunder he had taken. That is the extent of the information we have about this priest-king known as Melchizedek. But the author of Hebrews tells us that Jesus was appointed by God after the order of Melchizedek. In other words, He was of a different priesthood than that of Aaron and his sons. In the chapter seven of this letter, we are given more insight into who this man was and why Jesus was appointed high priest after his order and not that of Aaron:
He is first, by translation of his name, king of righteousness, and then he is also king of Salem, that is, king of peace. He is without father or mother or genealogy, having neither beginning of days nor end of life, but resembling the Son of God he continues a priest forever. – Hebrews 7:2-3 ESV
This does not mean that Melchizedek was a divine being who was never born or died, but that we have no record of his ancestry. He appears on the scene in the book of Genesis, then disappears. He serves as a foreshadowing of the King-Priest who was to come. He was the king of righteousness and the king of peace. Interestingly enough, Salem is the city that David would later make his capital and rename Jerusalem. And one day, Jesus will return and reign from the throne of David in Jerusalem when He establishes His Kingdom on earth. Unlike Aaron and his sons who served only as priests, Jesus was the King-Priest, appointed by God, and He received both titles when he ascended back to earth after His death and resurrection.
Jesus received these two divine appointments because He was obedient, faithfully completing the assignment given to Him by God the Father. Jesus did not simply offer sacrifices on behalf of the people as Aaron and his sons had done. Jesus offered Himself. He made the ultimate sacrifice of His own life. And even though He divine, the Son of God, as the human Jesus, “he learned obedience through what he suffered” (Hebrews 5:8 ESV). And His obedience, while it led to His death, resulted in His perfection, His glorification. He was raised from the dead and restored to His rightful place at the side of God the Father. And “he became the source of eternal salvation to all who obey him” (Hebrews 5:9 ESV). Jesus wasn’t just a different high priest than that of Aaron. He was a better high priest who offered a better sacrifice. His sacrifice was a permanent, once-for-all sacrifice that never has to be repeated. He was the sinless high priest who offered Himself as the unblemished Lamb of God for the sins of man. And as a result, those who place their faith in His sacrifice can share in His righteousness and have peace with God. We can be justified, made right with God. He is the great high priest.