The Israelites were chosen to bring forth the Savior reconciling God with His creation. Those Israelites who accepted Christ as fulfillment of the scriptures moved forward into the world to bring forth Christianity. Those who did not remained behind.
There are many Christians who believe the reason for chosenness ended with Jesus Christ.
OK, I see what you're saying.
I go with the many times God tells them they are His people and:
Matthew 5:17-20 King James Version (KJV)
17 Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil.
18 For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled.
But, beyond this I will refrain from having a discussion of religion.