And even they, if they do not continue in their unbelief, will be grafted in, for God has the power to graft them in again. (ESV)
Paul is speaking in this verse of the people of Israel. In the Old Testament we find God beginning a covenant relationship with Abraham. Abraham's descendants are the Jews, the people of Israel. In previous verses Paul has spoken of a tree with the root being Abraham. The descendants were to be the branches on that tree. Some, by their unbelief were branches that were broken off.
Paul is saying here that the Jews have not been given a death sentence. If they are a branch that is cut off because of unbelief there is a remedy; belief! God has always had a remnant of people in every generation who have placed their faith in him. We can get very discouraged, thinking that there is no one left on earth who is following the Lord. We would be wrong.
Perhaps you have known someone who has an unbelieving son or daughter. The parent prays daily for their wayward child. The child may wait until the funeral of the praying parent, but eventually places their faith in Christ. I am thankful that God does not turn away any sinner who comes to him in full repentance.
How about the Jews of today? Is there hope for them? Of course! There are many Jews who have come to belief in Jesus Christ as their promised Messiah. As Paul says, "God has the power to graft them in again." The important thing to realize is that there will be no grafting in of anybody unless there is repentance and faith in the finished work of Jesus Christ for salvation.
Do you know someone who is lost in unbelief? Do not give up on them. God is able. He is able to graft them into the same tree of faith as every other believer. The way is through Christ. Keep praying.