Paul’s warning in Rom. 11 is to Gentiles in general. The gospel of salvation through faith in Christ alone came to them BECAUSE of national Israel’s transgression of unbelief in her Messiah. The Gentiles now stand only by their faith (not works). Turn away from the gospel message of salvation through faith in Christ alone, either by outright rejection or corrupting it (both equal unbelief), and the Gentiles (as a people), like national Israel, will be broken off from the privilege of being in God’s favor.
Hi Apophasis!

I was wondering what happened to you. I agree with most of your analysis except for the above. Paul goes from generalities to specifics. The transition from generalties to specifics occurs in verses 17-22.
Romans 11:17-21
**17But if some of the branches were broken off, and you, being a wild olive, were grafted in among them and became partaker with them of the rich root of the olive tree,
18do not be arrogant toward the branches; but if you are arrogant, remember that it is not you who supports the root, but the root supports you.
19You will say then, “Branches were broken off so that I might be grafted in.”
20Quite right, they were broken off for their unbelief, but you stand by your faith Do not be conceited, but fear;
21for if God did not spare the natural branches, He will not spare you, either. **
Those Israelites that did not believe were cut off. Those who were cut off can be grafted in again,
provided they discontinue their unbelief.
**23And they also, if they do not continue in their unbelief, will be grafted in, for God is able to graft them in again. **
As I said in my previous posts, verses 17-21 only applies to Gentile Christians because only they can be grafted into the olive tree and only they **stand by their faith ** (v.20). If unbelieving Israelites were cut off from the tree because of their unbelief, unbelieving Gentiles cannot be grafted in. If they were not grafted in, then they cannot actually partake of the rich root of the tree and hence be holy. Moreover, you cannot be cut off if you were not grafted in first. And why should Gentiles who
stand by their faith fear (v.20)?
** 21for if God did not spare the natural branches, He will not spare you, either.
22Behold then the kindness and severity of God; to those who fell, severity, but to you, God’s kindness, if you continue in His kindness; otherwise you also will be cut off.**
Who are the “you” Paul is refering to? All Gentiles who stand by their faith (v.20). Verse 20 is crucial because it clearly shows that Paul has moved from general statements about Gentiles and Israelites, to specific statements about Gentile Christians. Believing Gentiles must also fear the possibility that they too will be cut off from the olive tree they were grafted in. An unbelieving Gentile has access to God’s kindness, but is not
in God’s kindness because he/she has no faith. If they are not
in God’s kindness, they logically cannot
continue in it. While Paul starts with generalities, the warning (v.v. 21-22) is specifically directed to Gentile Christians.
Now I ask you to do what you asked me to do. Do not filter this passage through your preconceived idead (i.e. eternal security).
God Bless,
Michael