God has not rejected the Israelites. To think such would be to purport that a loving and committed parent rejects their misbehaving child. They discipline the child. They remove the child from a situation where they may continue to harm themselves. They may even put the child in time-out, but they never stop loving the child nor does the child forgotten. As the child grows to adulthood and rejects the parent, the loving parent will allow them to go off, as we read in the story of the prodigal son as told by Jesus. But the ongoing desire of the parent is to welcome his child back and rejoice in their return.
Throughout the old testament we saw this play out with God’s chosen people, the Jews. They rebelled against God and turn away from Him and He turned them over to their wicked ways. He brought in conquering armies to carry them off in to exile. But, when they cried out to Him, He rejoiced in bringing them back home.
Would the situation with the Jews be any different during Paul’s time or today? God is unchanging and always faithful. His covenant is solid and true. He will discipline Israel. He will cause them to be jealous while they sit in time-out. He will allow them to turn away from Him and go off. But He will joyfully welcome them back home, back into sonship, back into His arms.
All Israel is all descendants of the faith of Abraham, not blood alone.
God is not cut off from them, they have God’s grace and mercy
God is merciful. He is also just but He chooses whom He choses and does what He does
God gave His one and only son to die and defeat sin so that He might take away the sins of the entire world, Jew and Gentile, all has been paid for all who believe