Paul is arguing that the nature of the tree has not been changed by the transition from the Levitical administration to the New Covenant. The Root is still Christ. The tree is still Israel—not the nation of Israel, but rather the person of Israel, the Lord Jesus. Christ is our Israel, and Christ is our only Israel. If we abide in Him permanently, we will bear fruit that remains. If we do not abide in Him permanently, we will be removed and burned.
