Since Scandal did not answer the question, I will. No. So, you see, a man that does not abide in Christ is like a branch that is cut off. The point in the comparison isn't that a branch was one time attached.
Non-sequitor. There is nothing in scripture telling us that Christ analogy is equal to that of Paul's in a completely different context. In light of Paul's explicit teaching regarding one being grafted back in again and even your own admission that Paul is addressing 'natural Israel' and not those abiding in Christ proves that is the case.
So, while their analogies are both related to trees and vines and their branches their is nothing connecting the two as being parallel comparisons, is there?
Secondly, there could be an argument made that one can appear to be abiding in Christ (as explained in Heb 6) from the human perspective who then would be "cut off" if they no longer abided in Him, but once again that would be a different theological matter being addressed all together.
Thirdly, the very concept of "redemption" and "reconciliation" is to bring one BACK into fellowship that was lost. Generally speaking, mankind LOST it's fellowship in Adam and thus is being brought back into relationship. So, in that regard all mankind was attached to the vine and were cut off due to the sin of the Fall and thus must be grafted back in. But, again, this is a different matter than the one Paul is addressing regarding Israel's being cut off in Romans 9-11.
As it is ludicrous to assert the branch that is cut off from the Vine ever truly abided
In regard to the text in question (Rom 11) when have I asserted that those grafted in to the tree were certainly abiding in Christ and saved? Haven't I consistently argued that being grafted into the vine represented one being able to see, hear, understand and thus respond to the revelation of God means of grace, His gospel?
I understand why you'd rather focus on another totally unrelated verse, though. It is clear the text of Romans 11 doesn't support your theory, so you'd rather put up a red herring and focus attention on a different matter all together.
That is not going to work.
And by the way, the Gospel Church is an entity, not a method or means.
The gospel, and the church that carries it, is the gracious means by which God has chosen to make his appeal to all mankind to be reconciled. No one, not even you, can deny that reality.
The 1st century Jew is either being blinded from that Gospel (hardened/cut off/stumbling) or He has been selected by God to be the "first fruit of the faith" (the remnant) and to carry the message to the rest of the world.