We learn in Matthew 2:14-15 that Jesus Christ is Israel and is the ultimate fulfillment of the prophecy in Hosea 11:1. Jesus came out of Egypt, passed through the waters, and was tempted in the wilderness, just like Israel of old. National Israel failed to fulfill the Covenant of blessing as God's people as we read in Exodus 19:1-6. National Israel broke the Covenant God made with them (Jeremiah 11:10). Jesus, however, kept the Covenant law perfectly. As a perfect sinless Jew, Jesus kept all of the 10 commandments and through Him all the ceremonial laws were fully satisfied. Jesus Christ fulfilled the law, succeeding where Old Covenant Israel had failed. He then took the law and nailed it to His cross (Colossians 2:14-17). Since only Jesus met all of the conditions of the Covenant, it's only in and through Him that the Covenant is fulfilled. True Israel does not exist outside of Jesus Christ!
The apostle Peter had Exodus 19:1-6 in mind when writing his first epistle and he saw it fulfilled in the Church through Jesus Christ (in whom we become a kingdom of priests and a holy nation). 1 Peter 2:5-9 helps one to see that the Covenant God made with Israel in Exodus 19 was fulfilled by the Church through Jesus Christ. Revelation 1:6 and 5:10 confirm that born again believers are kings and priests (royal priesthood) and are a holy nation unto the Lord. Romans 9:6-9 confirms that we are not considered children of God by being born a natural Jew, rather we are children of God through the singular seed of Abraham (Jesus Christ - True Israel). We become the Israel of God through Jesus Christ. The Jewish lineage lost relevance when Jesus Christ fulfilled what they failed to do. The only reason that lineage was of any significance and importance was because that's the lineage by which Jesus Christ would come, the singular seed of Abraham.
Jesus came to fulfill what was required for our salvation, but He also came to fulfill the requirements for obtaining the promises to Israel. The promises of God always had Jesus Christ in view! This is clearly seen as we read Galatians 3. Verse 16 establishes that the promises made to Abraham and his seed was always referring to Jesus Christ. Verse 29 then confirms a powerful truth regarding how we can only be Abraham's offspring spiritually through Jesus Christ, not through natural descent/bloodline. Jesus is Israel (a nation of one) and we enter this nation of One through obedient faith in the gospel (Acts 2:38).
God's dealing with the physical nation of Israel was only a type and shadow of God's plan for Israel ultimately being fulfilled in Jesus Christ and His Church (True Israel). Ephesians 1:3 declares that we receive the promised blessings of the Covenant in Jesus Christ. So the Church doesn't replace Israel, rather it's a continuation of Israel (all of the faithful who put their trust in a promised Deliverer). Israel is no longer identified as a nation of this world, but as a holy nation in Christ that is not of this world. Jesus Christ and the Church is the fulfillment of all Old Testament prophecies regarding Israel. Since Jesus is Israel and he fulfilled the law, there can be no separate plan of salvation outside of the Church for the so-called nation of Israel over in the middle east. All men must become the True Israel of God through faith in Jesus Christ (the fulfillment of Israel). There aren't two Israel's with two separate bodies. The Israel of God is the Church and is one body in Jesus Christ!