Romans 11:22-25

So you see that God is kind and also very strict. He punishes those who stop following him. But God is kind to you, if you continue following in his kindness. If you do not, you will be cut off from the tree. And if the Jews will believe in God again, he will accept them back. God is able to put them back where they were. It is not natural for a wild branch to be part of a good tree. And you who are not Jews are like a branch cut from a wild olive tree and joined to a good olive tree. But since those Jews are like a branch that grew from the good tree, surely they can be joined to their own tree again. I want you to understand this secret, brothers and sisters, so you will understand that you do not know everything: Part of Israel has been made stubborn, but that will change when many who are not Jews have come to God.