Perhaps this secret has not been told to you?
Produce the Scripture where God says that the death of Jesus Christ means that His explicit promises to Israel are no longer in effect.
Now if you can't find the Scriptures, then your belief that the fact that Jesus' death makes God's promises to Israel null and void are nothing more than man-created doctrine that is in direct contradiction to the Word of God. And whatever is in conflict with what God has said is demonic.
This shouldn't be a problem. If God agrees with your doctrine and beliefs, then the Scripture is there.
As long as you can't produce the validation from God, you have a false doctrine.