For it was fitting that we should have such a high priest, holy, blameless, undefiled, separated from sinners, and exalted above the heavens. Unlike the other high priests, he has no need to offer sacrifices day after day, first for his own sins, and then for those of the people; this he did once for all when he offered himself. For the law appoints as high priests those who are subject to weakness, but the word of the oath, which came later than the law, appoints a Son who has been made perfect forever. ~ Hebrews 7:26-28
There are many theories about what happened with Christ's work on the cross. They are called Atonement theories - how Christ atoned for our sins with his death. (how we are made "one" or whole with his death...ie: at-one-ment).
Many of those theories expand upon the notion here of "sacrifice" that the writer to the Hebrews espouses. (note: for some understanding about each of the seven theories, you can get a nice summary of them here: https://www.sdmorrison.org/7-theories-of-the-atonement-summarized/) It's important to note that these theories are just that: theories. We live in an era where the Penal Substitutionary theory holds the most sway. However, it is, like the others, just a theory. (and one that for me doesn't make a whole lot of sense since it implies God is just angry and wrathful and can only forgive by killing Jesus, which the experience of the Hebrew people shows is not the case. God's been in the forgiving and loving business for a long, long time).
For those living in the era of 1st century Judaism and Jewish Christianity, the metaphor of sacrifice made sense. It is what had been happening in the temple for generations as a way to appease God and seek forgiveness.
But for us, maybe it doesn't make so much sense.
I have my own ideas about which theory makes the most sense to me, and maybe as you read through some of these you'll find that one makes more sense to you as well. But in the meantime, this is a quote that I've found very helpful about what happened with Jesus' death on the cross. It is from a popular Christian podcaster named Mike McHargue (AKA Science Mike).
“The cross was not God’s invention—it was ours. The cross was an instrument of torture, a method of intimidation created by an empire that needed to keep its conquered cities in check. In all our need for an eye for an eye, I have to wonder sometimes if Jesus’ sacrifice on the cross is an answer not to God’s wrath, but to ours. I have to wonder if God, having listened to us cry for blood, decided to offer his own. Perhaps Jesus hung on a cross to demonstrate the inevitable outcome of retributive justice in the face of an empire that used violence to expand, that survived only by placing societies under its oppressive heel. Jesus didn’t hold up a sword in response to a sword. He took the sword into His side, and in doing so, revealed our brutality for what it was.”
Lord make me one with you, even if I can't understand how it happens. Amen