Bob, the covenant with Issac is thru lineage.
Read Matthew Chapter 1 verses 1 through 16. Emphasis on verse 16.
Christ said to take the message first to the Jew, and then the gentile.
Context is everything. If Salvation thru the Cross isn't for all of man, then the New Testament is a lie.
CHRIST SAID: "NO MAN" COMES UNTO THE FATHER EXCEPT BY "ME"
He didn't say: except for the Jews, I gave them a different deal.
Israel has abandoned God several times in scripture. "Its In Your Bible" and everytime they turned back to God in times of tribulation.
They in the end, once again, will come back in tribulation when they realize that their salvation can only be, by recognizing Christ as their Savior.
SPECULATION on Judaism mixing with Christianity is a fools errand, and a misleading fallacy to those unstudied seeking salvation.
Everytime Israel has turned away from God, He has punished them, and they have always came back to Him in their time of tribulation.
NUTHIN HAS CHANGED.
They denied Christ, ordered by the Sanhidrin through Pilate to kill Him.
Look what has happened to the Jews for the last 2,000 years. Scattered to the four corners of the world, persecuted, and killed. Constantly under attack, and their still denying Christ.
Once again, at some time in the future, they will be brought to their knees in judgment for their denial of Christ, and once again, when tribulation becomes unbearable, they will again turn to Christ for their Salvation.
It's all in the Bible. It tells you how it ends.