God changes the Law at times.
At first, God tells all the Israelites they will be His priests. (Ex.19:5-6) Soon after, the people make a golden calf and only the tribe of Levi agrees to stand with Moses for the Lord.
Through Moses, God set up a priesthood to operate exclusively under the tribe of Levi and it was done in conjunction with the Law.
After having established Levites as priests perpetually, fast forward to Jesus as explained in Hebrews 7. Now via an oath, God suddenly breaks through this perpetuality and starts a new & final priesthood with Jesus being the High Priest forever. He changes the Law.
“Now if perfection was through the Levitical priesthood (for on the basis of it the people received the Law), what further need was there for another priest to arise according to the order of Melchizedek, and not be designated according to the order of Aaron? For when the priesthood is changed, of necessity there takes place a change of law also.”
No longer is this according to the Law, where only Levites can be priests. This is according to some external-to-the-Law oath. God is clearly above the Law, not equal to it. And as indicated in the text below, AFTER the Law, as in post-Law.
“For the Law appoints men as high priests who are weak, but the word of the oath, which came after the Law, appoints a Son, made perfect forever.”
“Why then the law? It was added because of transgressions, until the offspring should come to whom the promise had been made, and it was put in place through angels by an intermediary. Now an intermediary implies more than one, but God is one. Is the law then contrary to the promises of God? Certainly not! For if a law had been given that could give life, then righteousness would indeed be by the law. But the Scripture imprisoned everything under sin, so that the promise by faith in Jesus Christ might be given to those who believe. Now before faith came, we were held captive under the law, imprisoned until the coming faith would be revealed. So then, the law was our guardian until Christ came, in order that we might be justified by faith. But now that faith has come, we are no longer under a guardian, for in Christ Jesus you are all sons of God, through faith. For as many of you as were baptized into Christ have put on Christ. There is neither Jew nor Greek, there is neither slave nor free, there is no male and female, for you are all one in Christ Jesus. And if you are Christ’s, then you are Abraham’s offspring, heirs according to promise.”
The Law was ADDED, not always existent. The Law was TEMPORARY, added because of sin and until Jesus came. The Law prior to Jesus was meant as a guardian to keep hold on us until it was time for Jesus at which time faith would be enacted and law would be done with. This scripture clearly and definitively expresses an after-Law time indicated and initiated or culminated by the coming of Jesus. Like it or don’t, but it is clear.