That's not to say He uses the same operation. There's one method (Christ) now. Jesus' calling is irrevocable. God swore an oath , which is something He never did with Aaronic priesthood (Heb. 7:21).
Frankly, this is so basic, I can't hardly believe you don't know this. I'm sure that sounds "stupid" on my part, but it's just amazing to me.
Deut 10:8 At that time [at Sinai] the LORD separated the tribe of Levi, to bear the ark of the covenant of the LORD, to stand before the LORD to minister unto him, and to bless in his name, unto this day.
There's no such thing as the other 11 tribes being priests. To enter the holy place would have invited stoning. Only Levi descendants tended the altars.
Why did God separate Levi? Because the others refused to hear, feared the fire (of Pentecost).
Believers in Christ, however, have not come to Sinai. That is not our model, our order. We have come to Zion. The fire of pentecost burned in their hearts as living witnesses to God's glory. Christ was of Judah, was of the order of Melchizedek. The priesthood has changed. The law has changed. Heb. 7:12. The former covenant is gone v18. It was ineffective v19. He says there will be a new one 8:8. He regarded them/it not v9. The old vanishes v13.
Our order is Melchizedek with Christ the high priest and we the priesthood of believers.
The only thing that is 'basic' about your view is that it's basically wrong.
When Paul cites that God's gifts and calling are irrevocable in Romans 11, his context is God's covenant with the Jewish forefathers, not the new covenant with Christ.
The other 11 tribes were not Levitical priests. They were the priesthood of the nation. Their role was not to enter the holy place. It was to be a witness to the rest of the nations.
The Israelites did not refuse to hear God. They heard him plenty. Thunder, as I recall.
Try as you like, you cannot rewrite the story that the Israelites were to be the receivers of God's conversation. They were to be witnesses to God's conversation with Moses, so they would believe Moses and listen to him. Exodus 19 "9 And the LORD said to
Moses, "
Lo, I am coming to you in a thick cloud, that the people may hear when I speak with you, and may also believe you for ever."
You insist that God came to speak to the Israelites directly. Scripture says he came to speak to Moses directly, and the Israelites were only to hear God speaking to Moses.
You insist that the Israelites refused to hear God. They do hear God -- speaking to Moses with a voice of thunder.
You insist that because the Israelites refuse to speak to God directly, he revokes His covenant with them to be the priesthood of the nation. God didn't ask to speak to the Israelites directly. He came to speak to Moses directly.
You insist that God revokes their priesthood of the nation. That is never found in Scripture.
You insist that God establishes the Levites as a 'substitute' for them. God never indicates he is establishing the Levitical priesthood for this reason.
As long as your foundation is all made up of stuff that is either not in Scripture or directly contradicts it, you've got nothing. I have no doubt you'll keep spouting that the Israelites refused to hear God so he revoked their covenant. That will never make it true. If St. Paul knows that even when the Jews reject Christ God yet honors his covenant with their forefathers, you are on dangerous ground by claiming he does not.
Our order is indeed Christ as high priest, we are indeed a priesthood of believers. And there is indeed a priestly service necessary so that the offering of the Gentiles is acceptable (Romans 15:16) that is foretold by the prophet Isaiah (66:21). And it is indeed an effective covenant. Not because we are so much more effective as being a priesthood of believers than Israel was. But because, and only because, Christ is our high priest. He is the pure sacrifice offered on behalf of the Gentiles, which is what makes us acceptable to God.