Hebrews 7:11-17 (HCSB)
If then, perfection came through the Levitical priesthood (for under it the people received the law), what further need was there for another priest to appear, said to be in the order of Melchizedek and not in the order of Aaron? For when there is a change of the priesthood, there must be a change of law as well. For the One these things are spoken about belonged to a different tribe. No one from it has served at the altar. Now it is evident that our Lord came from Judah, and Moses said nothing about that tribe concerning priests.
And this becomes clearer if another priest like Melchizedek appears, who did not become a priest based on a legal command concerning physical descent but based on the power of an indestructible life. For it has been testified:
    You are a priest forever
    in the order of Melchizedek.

Wanting things to stay the same is a significant part of human nature. And that is true in every area of our lives. Even if something does not work as well as it could or should, there is a tendency to resist change, to keep things the same. We are familiar with the way things are and have been, and it feels normal to us.

It was the same way with many of the Jewish people. The idea that the old priesthood could be supplanted by something new, that the old sacrifices could be replaced by a once-for-all sacrifice, was almost inconceivable. And it was uncomfortable to even contemplate.

But the cold, hard fact was that the Levitical priesthood was designed to be eclipsed by the high priesthood of the Messiah. The old Levitical priesthood was led by weak, fallible, sinful men; the new Melchizedek priesthood was led by God in the flesh, Jesus, the Messiah. The Levitical priesthood could provide atonement; the new Melchizedek priesthood could provide both atonement and transformation. The Levitical priesthood was a shadow of what was to come; the new Melchizedek priesthood is the reality, the ultimate fulfillment of all that had come before.

Jesus did not belong to the line of Aaron, to the clan of Zadok from whom at the Levitical high priests were selected. When the Messiah came, he broke the mold, which was essential. The Levitical priesthood had become hidebound, almost fossilized by the rites, rituals, and traditions that had been passed down for 1500 years. The new covenant could not be realized within the old structures.

So, God did the new thing that had been foretold for thousands of years. He recreated the entire sacrificial system with the death and resurrection of Jesus. He instituted a new priesthood, not hereditary like the old, but with one divine High Priest who would serve forever.

Father, we do tend to resist change, even when it is clearly change for the better. But when Jesus came, he brought a more effective priesthood, one that can actually make us alive, transform us from the inside out, and give us hope and a future that will last for all eternity. Thank you so much for this amazing reality that we get to live in, starting here and now. Amen.