Matthew 23:39 'For I tell you, you will not see me again, until you say, ‘Blessed is he who comes in the name of the Lord.’
Lord Jesus will not return until the Jews say '‘Blessed is he who comes in the name of the Lord.’ Israel is the key for the Lord's return, without them repenting, Lord Jesus will not return. You need the nation of Israel.
Furthermore, the promise given to Abraham in Genesis 15 has not been fulfilled. Genesis 15:18 'To your offspring I give[
c] this land, from the river of Egypt to the great river, the river Euphrates, 19 the land of the Kenites, the Kenizzites, the Kadmonites, 20 the Hittites, the Perizzites, the Rephaim, 21 the Amorites, the Canaanites, the Girgashites and the Jebusites.”'
Israel has has never possessed the specific boundaries that God promised in Genesis 15:18-20. Not even Solomon ruled over this particular area Although he did reign from the River of Egypt to the Euphrates, he did not hold the area from Mount Hor to Hazarenan (
Numbers 34:7–9)—into present-day Lebanon and Syria. In addition, the covenant God made with Abraham was that he and his descendants would have the land forever
You also have the war in Ezekiel 38 that did not happen yet. For that, you need a nation Israel.
God has also given His word that the nation of Israel will never cease as long as the sun still shines by day and the moon and stars still shine by night (
Jeremiah 31:35–37).
God has not abandoned Israel, as we see in Hosea 2 19 And I will betroth you to me forever. I will betroth you to me in righteousness and in justice, in steadfast love and in mercy. 20 I will betroth you to me in faithfulness. And you shall know the Lord. 21 “And in that day I will answer, declares the Lord, I will answer the heavens, and they shall answer the earth, 22 and the earth shall answer the grain, the wine, and the oil, and they shall answer Jezreel, 23 and I will sow her for myself in the land. And I will have mercy on No Mercy, and I will say to Not My People, ‘You are my people’; and he shall say, ‘You are my God.’”
Romans 11:17 “And if some of the branches were broken off,” – that talks about Israel being broken off – “the trunk is the root of blessing.” Israel was plugged into God’s blessing, but Israel got cut off. They got cut off because of – what? – unbelief.
“And thou being a wild olive tree were grafted in.” Who’s that? Gentiles. Israel was cut off from the root of blessing because of unbelief, Gentiles were grafted in. So he says, “You were grafted in among them, and with them partakest to the root and fatness of the olive tree, but don’t get proud about it. Don’t be proud” – verse 19 – “and say, ‘The branches were broken off that I might be grafted in.’ Well, because of unbelief they were broken off. And just remember, you only stand by faith. Don’t be high-minded, but fear; for if God spared not the natural branches, take heed lest He also spare not thee.”
Verse 24, “For if thou were cut out of the olive tree” – now watch – “and grafted in contrary to nature, how much more shall these who are the natural branches be grafted into their own olive tree.” Now watch, Israel was cut off and new branches, the church, grafted in. The church someday will be severed, Israel will be regrafted in. Does that tell you there is a difference between Israel and the church? Of course it does. The church has in the place of blessing been grafted in. The day will come when the Lord takes the church. Israel will be grafted back in during the tribulation, and salvation will come to Israel.
Verse 25: “I would not, brethren,” – here he explains it spiritually – “I would not, brethren, you should be ignorant of this mystery, lest you should be wise in your own conceits;” – blindness in part has happened to Israel – “only until the fullness of the Gentiles, only until all of the branches have been grafted in the church is complete. Then,” – 26 – “then all Israel” – what? – “shall be saved.” Grafted back in again.
Now the very fact that Paul takes pains to make a distinction between the church and Israel indicates there is a distinction. And the history of Israel in the trunk of blessing is at the beginning and the end of God’s dealing, and the grafting in is somewhere in the middle. It began at Pentecost, it ends at the rapture, and Israel’s grafted back in. So the very statements of Romans 11 indicate that there is a difference, and that the church has parenthetical character.
Those who says that today's Israel has nothing to do with the OT Israel are simply wrong.