This topic seems to come up a lot. This post is more or less taken directly from "The Religion of the Apostles" by Fr Stephen De Young. Great book, by the way.
The word Church is the English translation of the German translation of the Greek word ekklesia, meaning assembly (you'll recognize iglesia in Spanish borrows it directly from Greek). Its the word used in the Greek old testament to describe the assembly of Israel, God's people. In the New Testament this same word continues to be used to describe God's people, Israel restored. The Church did not replace Israel, is not the new Israel. It is Israel, in continuity - the assembled people of God. And it isn't that Israel stopped being something determined by ethnicity, it's that Israel was never about ethnicity and for only a brief period of time was it about a nation-state.
After Babel the Most High God assigned the nations to regent angels or gods (cf Deut 32:8). To begin His work to reclaim and save mankind and His creation He didn't pick from one of those nations to begin, but made a new nation. As St Paul says, He is "the God who gives life to the dead and calls into being things that were not." The people Israel came from and through Abraham, who is the father of all who believe in God. There is a parallel between Moses who redeems the sons of Jacob from Egypt through Pascha to form a new nation Israel with a covenant at Pentecost and Christ Jesus who comes to redeem the faithful remnant in Judea through Pascha to reconstitute Israel with a covenant at Pentecost. At the first, the people of Israel were an ethnically mixed group not formed by a certain tribe or a certain place but formed by their faithfulness to God. And at the reconstitution the same is true. Of the several nations of Abraham, Israel comes through the unique sonIshmael Isaac, and is culminated in the unique Son Jesus Christ. And so the purpose of Israel is to save the whole world - "Salvation comes from the Jews."
The mixed multitude who leave Egypt as Israel are not defined by where they live (a local god) or their ethnicity but by faithfulness to God. A "mixed multitude" goes out from Egypt, and many Israelites are clearly not ethnic descendants of Abraham (e.g., Caleb who is a Kenizzite). This new people Israel were formed by the Passover and covenant at Pentecost. They along with the other descendants of Abraham (such as Edom from Esau) inherit the land as told in Joshua. All the promises of the land were fulfilled (Josh 21:43). They lived for a time as tribes, then became a combined kingdom under Saul, then David and Solomon. After Solomon most of Israel (the ten tribes who made up the northern kingdom) broke away and immediately fell into apostasy. They were scattered after centuries of faithlessness and were lost into the gentile population when the Assyrians depopulated the land. Those ten tribes were prophesied to be renewed from the gentiles in the prophets (Jer 31:3-6, 50:4-5, Ezek 37:15-19) under the messianic king (Ezek 37:23-24). This restoration requires gentiles to come into Israel again, with a new Pascha, and a new Pentecost. Israel is the Lord's inheritance from the nations - and after the Messiah arises to judge, His inheritance is all nations (Ps 82). This is why the NT presents the death and resurrection of Jesus as a new Passover, Exodus, and Pentecost (John 1:29, Matt 26:2, Mark 14:1, John 19:14, 1 Cor 5:7, Act 20:28, 1 Pet 1:9,19, 1 Cor 10:1-4, Matt 26:28, 1 Cor 11:25, Heb 12:24).
St Paul in Romans answers the question of whether the dissolution of the Norther Kingdom meant God's promises to Israel failed. He raises a few examples to answer. First, the Lord who is sovereign allowed Pharaoh to be powerful even though he was evil - he was blessed by God who is merciful and loving even to disobedient humans. But in his evil, Pharaoh brought judgment on himself, and God used him as an example to judge the gods of Egypt (of which Pharaoh was one).
Next he mentions the potter analogy from Jeremiah. Yahweh shapes nations like a potter shapes clay, and if a nation is evil he breaks it down and re-shapes it (Jer 18:1-10). God as potter took these vessels of wrath and used the judgment of their faithlessness to prepare vessels of mercy which is both times Israel; the first, then the renewed. God's patience with these vessels of wrath is precisely for His mercy to be shown to the whole world, through His people Israel.
Likewise the analogy of the olive tree, where God allows the unfaithful branches to grow in order to prune them, to let faithful branches be grafted in. But these faithful were coming from all nations, including the ones that the faithless tribes were dispersed into. And so, in the end All Israel (even the lost tribes) is saved (Romans 9:25-26, Romans 11:25-27, Hoseah 1:10, 2:23) And this ongoing until the Israel is filled up with "the fullness of the gentiles" - the whole world. Eventually God inherits all people, and the faithful people of God come from all nations (Luke 21:24, Matt 28:19). The Church IS Israel.
The word Church is the English translation of the German translation of the Greek word ekklesia, meaning assembly (you'll recognize iglesia in Spanish borrows it directly from Greek). Its the word used in the Greek old testament to describe the assembly of Israel, God's people. In the New Testament this same word continues to be used to describe God's people, Israel restored. The Church did not replace Israel, is not the new Israel. It is Israel, in continuity - the assembled people of God. And it isn't that Israel stopped being something determined by ethnicity, it's that Israel was never about ethnicity and for only a brief period of time was it about a nation-state.
After Babel the Most High God assigned the nations to regent angels or gods (cf Deut 32:8). To begin His work to reclaim and save mankind and His creation He didn't pick from one of those nations to begin, but made a new nation. As St Paul says, He is "the God who gives life to the dead and calls into being things that were not." The people Israel came from and through Abraham, who is the father of all who believe in God. There is a parallel between Moses who redeems the sons of Jacob from Egypt through Pascha to form a new nation Israel with a covenant at Pentecost and Christ Jesus who comes to redeem the faithful remnant in Judea through Pascha to reconstitute Israel with a covenant at Pentecost. At the first, the people of Israel were an ethnically mixed group not formed by a certain tribe or a certain place but formed by their faithfulness to God. And at the reconstitution the same is true. Of the several nations of Abraham, Israel comes through the unique son
The mixed multitude who leave Egypt as Israel are not defined by where they live (a local god) or their ethnicity but by faithfulness to God. A "mixed multitude" goes out from Egypt, and many Israelites are clearly not ethnic descendants of Abraham (e.g., Caleb who is a Kenizzite). This new people Israel were formed by the Passover and covenant at Pentecost. They along with the other descendants of Abraham (such as Edom from Esau) inherit the land as told in Joshua. All the promises of the land were fulfilled (Josh 21:43). They lived for a time as tribes, then became a combined kingdom under Saul, then David and Solomon. After Solomon most of Israel (the ten tribes who made up the northern kingdom) broke away and immediately fell into apostasy. They were scattered after centuries of faithlessness and were lost into the gentile population when the Assyrians depopulated the land. Those ten tribes were prophesied to be renewed from the gentiles in the prophets (Jer 31:3-6, 50:4-5, Ezek 37:15-19) under the messianic king (Ezek 37:23-24). This restoration requires gentiles to come into Israel again, with a new Pascha, and a new Pentecost. Israel is the Lord's inheritance from the nations - and after the Messiah arises to judge, His inheritance is all nations (Ps 82). This is why the NT presents the death and resurrection of Jesus as a new Passover, Exodus, and Pentecost (John 1:29, Matt 26:2, Mark 14:1, John 19:14, 1 Cor 5:7, Act 20:28, 1 Pet 1:9,19, 1 Cor 10:1-4, Matt 26:28, 1 Cor 11:25, Heb 12:24).
St Paul in Romans answers the question of whether the dissolution of the Norther Kingdom meant God's promises to Israel failed. He raises a few examples to answer. First, the Lord who is sovereign allowed Pharaoh to be powerful even though he was evil - he was blessed by God who is merciful and loving even to disobedient humans. But in his evil, Pharaoh brought judgment on himself, and God used him as an example to judge the gods of Egypt (of which Pharaoh was one).
Next he mentions the potter analogy from Jeremiah. Yahweh shapes nations like a potter shapes clay, and if a nation is evil he breaks it down and re-shapes it (Jer 18:1-10). God as potter took these vessels of wrath and used the judgment of their faithlessness to prepare vessels of mercy which is both times Israel; the first, then the renewed. God's patience with these vessels of wrath is precisely for His mercy to be shown to the whole world, through His people Israel.
Likewise the analogy of the olive tree, where God allows the unfaithful branches to grow in order to prune them, to let faithful branches be grafted in. But these faithful were coming from all nations, including the ones that the faithless tribes were dispersed into. And so, in the end All Israel (even the lost tribes) is saved (Romans 9:25-26, Romans 11:25-27, Hoseah 1:10, 2:23) And this ongoing until the Israel is filled up with "the fullness of the gentiles" - the whole world. Eventually God inherits all people, and the faithful people of God come from all nations (Luke 21:24, Matt 28:19). The Church IS Israel.