Deuteronomy 32:21 They have moved me to jealousy with that which is not God; They have provoked me to anger with their vanities: And I will move them to jealousy with those which are not a people; I will provoke them to anger with a foolish nation.
God’s people didn’t show Him the respect that He deserved. They would go after other gods and worship them. They were provoking Him to jealousy. So He warns them that He will do the same when He calls out a people that are not a people to move them to jealousy. He will use a foolish nation to provoke them to jealousy. That is what will cause Israel to return and do right after He has taken the church out.
Paul cites this verse when He is explaining why God is using the church.
Romans 10:19 But I say, Did not Israel know? First Moses saith, I will provoke you to jealousy by them that are no people, and by a foolish nation I will anger you.
The church was a new people, a foolish nation. They had been far from God but now they were brought together. The middle wall of partition was broken down. Jews and Gentiles would form a new body called the church.
The foolishness of Israel would cause God to bring the church into existence. The church would provoke the Jews to jealousy and they will once again do their duty of sharing the gospel.