Main point summary
As a faithful Christian, Faith in receiving the promises originally promised only to the physical Jew should not be marked by pride but by fear and respect in the Lord as one who kindly provides for those who trust in faith but will not spare anyone who falls into unbelief; Neither Jew nor Gentile.
y If the dough offered as firstfruits is holy,
so is the whole lump,
and if the root is holy,
so are the branches.
But if z some of the branches were broken off,
and you, a although a wild olive shoot,
were grafted in among the others
and now share in the nourishing root 1 of the olive tree,
do not be arrogant toward the branches.
If you are,
remember it is not you who support the root,
but the root that supports you.
Then you will say,
“Branches were broken off
so that I might be grafted in.”
That is true.
They were broken off
because of their unbelief,
but you b stand fast through faith.
So c do not become proud,
but d 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,
e provided you continue in his kindness.
Otherwise f you too will be cut off.
And g 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.
If the forefathers are counted as holy in God's eyes, then the Jewish descendants will be counted as holy as well.
There is no reason for a Gentile to be arrogant toward Jews about receiving the promises formerly reserved for them. For God's promise to the Jews (ie the messiah, the scriptures, the cross, propitiation) is what gives a Gentile Christian life.
Gentile Christian: do not be arrogant toward those Jews who have fallen, since their promises from God is what gives you life. Rather fear and respect the God who will deal severely with those who live in unbelief but act kindly toward those who believe, even to Jews who return to belief.