Peter Pett's Commentary on 1 Pet. 2:9 shows the church to be
a continuation of true Israel, a succession of Israel; NOT A REPLACEMENT! The OT prophets spoke of the New Covenant assembly, NOT some renewed Jewish state in our future. This is just a portion of Pett's comments.
"But you are a chosen race, a royal priesthood, a holy nation, God’s own people, that you may declare the wonderful deeds of him who called you out of darkness into his marvelous light. Once you were no people but now you are God’s people; once you had not received mercy but now you have received mercy." (1Pet 2:9-10, RSV)
"Every phrase in this verse is pregnant with meaning, for He is declaring what
the church, as the continuation of the true Israel, really are. They are:
· ‘An elect race (a chosen race).’ Initially God had chosen Israel as ‘His elect, His chosen’ (Isa 42:1; Isa 45:4), expanded in Isa 43:20 b LXX into His ‘elect race’ Outwardly it appeared as though it was the whole nation which were being described, but a careful reading of the Old Testament reveals that the elect were really seen as those who responded to the covenant (e.g. Isa 65:9; compare Isa 4:3-4; Isa 6:11-13 and often). They were the ‘seven thousand who had not bowed the knee to Baal’ (1Ki 19:18). ‘Israel’ was a fluid concept. Initially it was made up of the households of the Patriarchs which included many foreigners who were servants and slaves in the family tribe. It was never strictly true that all Israel were directly descended from the Patriarchs, except by adoption. Subsequently any foreigners who wished to enter the covenant could do so by living among His people and being circumcised (Exo 12:48 - although there were certain limitations and exceptions - Deu 23:1-8). And many did so, including the mixed multitude of Exo 12:38. The essential point was that ‘Israel’ was made up of those who were, at least theoretically, truly committed to the covenant, of whatever nationality. And in contrast any of Israel who rejected the covenant by their words and actions were ‘cut off’. That is why God could speak of them as ‘not my people’ (Hos 1:10). Notice Paul’s vivid picture of the branches being cut off from, or grafted into, the olive tree (Rom 11:17-28).
But now, says Peter, it is the church who are the true succession of Israel. It is they who are now His ‘elect race’. It is they who are the continuation of the true Israel. It is only they who are true to the covenant. They are the new nation, springing out of the old, spoken of by Jesus in Mat 21:43, and founded on Jesus the Jew and the Jewish Apostles and the early Jewish church. And they are thus God’s chosen ones, set apart to fulfil His purposes for the world. They are the true children of Abraham (Gal 3:29), chosen by God and precious. They are the true ‘chosen race’.
‘A royal priesthood.’ His people are also a ‘royal priesthood’. Compare Rev 1:6. This is clearly Peter’s interpretation of ‘a kingship of priests’ (Exo 19:6), the latter stated at a time when each family head was a priest. The idea was that Israel would be priests to the nations in a royal capacity, because they represented the King. This may well also have in mind the royal priesthood of David, who, once he became king of Jerusalem, thereby became an intercessory priest ‘after the order of Melchizedek’ (Psa 110:4, compare the king of Jerusalem in Gen 14:18; and see Zec 6:13; Heb 6:19 to Heb 7:25). This ‘royal priesthood’ is not a priesthood of sacerdotal duties. That is not in mind here. It is a priesthood of outgoing responsibility. Like those who bore the vessels of the Lord they were to go out in order to proclaim God’s truth with the certainty that God would go with them (Isa 52:11-12; compare Isa 2:3). For priests were also essentially involved, among other things, in preaching, teaching, interpreting the Law and interceding for the people, and as royal priests the church were to do the same from a new position of royal authority. Indeed the future of Israel had very much been seen as one of ‘priesthood’ (Isa 61:6), which was also to involve Gentiles (Isa 66:21), and here it finds its fulfilment through the church, the new Israel."
https://www.studylight.org/commentaries/eng/pet/1-peter-2.html