The new covenant is written in Jer 31:31-34 and again by Paul in Hebrews 8:8-12 ... if one reads it is is an unconditional [unmerited] forgiveness of BOTH Houses of still-divided Israel, both the Jews [visible Israel , the House of Judah] and the non-Jewish Hous of Israel , that disappeared in being scarttered amongst all the gentile nations ...
The task of the messiah [the annointed one, in Greek 'christois', Christ] in the OT and the NT, is to gather the two Houses together as one nation and be one king over them and so make them a kingdom of priests as promised by God Himself :-
Ezekiel 37:22 And I will make them one nation in the land upon the mountains of Israel; and one king shall be king to them all: and they shall be no more two nations, neither shall they be divided into two kingdoms any more at all:
Exodus 19:6 And ye shall be unto me a kingdom of priests, and an holy nation. These are the words which thou shalt speak unto the children of Israel.
Jesus identifies with this task as messiah by saying that he is only sent to the lost sheep of the House of Israel [and he uses the Jews as disciples to continue the work after his death :-
Matthew 15:24 But he answered and said, I am not sent but unto the lost sheep of the house of Israel.
Matthew 10:6 But go rather to the lost sheep of the house of Israel.
Acts 2:36 Therefore let all the house of Israel know assuredly, that God hath made that same Jesus, whom ye have crucified, both Lord and Christ.[messiah]
When he returns we find that ALL those he takes are indeed of TRIBAL Israel, by name of the sons of Jacob , from both Houses ... thus indeed a remnant of Israel are the only firstfruits sealed in the spirit [Rev 7:3-8]
So why does he not take all Israel, since Paul says clearly that all Israel are saved , and Moses reports that the whole nation will be holy priests in the kingdom of the messiah ? :-
Romans 11:26 And so all Israel shall be saved: as it is written, There shall come out of Sion the Deliverer, and shall turn away ungodliness from Jacob:
Paul then clearly associates Jesus with the deliverer of Israel who emerges from Jerusalem...
So let us see, God sets up His kingdom after Jesus' return and all israel are taken as priests in the kingdom once it is established in other than the hearts of those of Israel who are mentioned in the new covenant of grace to Israel's two Houses...
clearly a priesthood needs a populace to minister too, its function is to serve, and the only ones they can serve are the masses of the gentiles ... and indeed that is what comes afterward [Rev 7:9-10] , inumerable gentiles all asking for salvation to God, but they are saved nly after the priesthood... rather obvious really ,but it says so very clearly at the beginning of Rev 7:9 and most people ignore that...
So why?... again it is rather obvious, most of Israel died as sinners not believing in Jesus the messiah , so theycannot live until after the SECOND resurrection [the first being for the firstfruit saints who died before Jesus returned] ... thus the priesthood of the whole of Israel cannot even be set up until after the second resurrection, nor can the sinners of the gentiles live until then either, since Jesus has said that he cannot take ANY sinners at his return :-
Matthew 7:23 And then will I profess unto them, I never knew you: depart from me, ye that work iniquity.[sin!]
So that is whgy most Jews do not yet accept Jesus, he has not shown them that he is their king ,their messiah , and they do not realise that he will NOT be their king in this earth! :-
John 18:36 Jesus answered, My kingdom is not of this world:
NOR do manu Jews or paganised house of Israel know that they will be kings and priests on the earth, but thuis the new earth , not THIS earth :-
Revelation 5:10 And hast made us unto our God kings and priests: and we shall reign on the earth.
Thus christian priests do not realise that no priests of the new covenant are ordianed by God yet at all [christian priests are all ordiined by men, sinners! , and are not members of the order of Melchisedec, but belong to human orders of sinner priests]
It is thus very interesting that neither Christians nor Jews understand the scriptures of God yet .... but God has revelaed all truth to His few saints of this world [John 16:13]