We are all one in Christ
Correct, but we Gentiles are grafted in to the believing Jewish Tree. The New Covenant (Jeremiah 31) is made with believing Israel / Judah, we are grafted in forming the Church. Jesus is coming back with the Church to reclaim His land and establish His kingdom. A remnant of unbelieving Jews will be saved (grafted back in) when they recognize who Jesus is…(Zechariah 12)