That is true. They were broken off because of their unbelief, but you stand fast through faith. So do not become proud, but fear.
For if God did not spare the natural branches, neither will he spare you.
Note then the kindness and the severity of God: severity toward those who have fallen, but God's kindness to you, provided you continue in his kindness. Otherwise you too will be cut off.
And even they, if they do not continue in their unbelief, will be grafted in, for God has the power to graft them in again.
For if you were cut from what is by nature a wild olive tree, and grafted, contrary to nature, into a cultivated olive tree, how much more will these, the natural branches, be grafted back into their own olive tree.
Lest you be wise in your own sight, I do not want you to be unaware of this mystery, brothers: a partial hardening has come upon Israel, until the fullness of the Gentiles has come in.
And in this way all Israel will be saved, as it is written, The Deliverer will come from Zion, he will banish ungodliness from Jacob;