Why make the Christian believer different from the unbeliever?
Israel had a clear advantage while the Gentiles were at a clear disadvantage.
But not all who are called Israel ARE Israel - Within the microcosm of the nation of Israel is the picture of believers and unbelievers. The circumcision is of no avail. A sinning unbelieving Israelite has no more advantage than an unbelieving gentile.
The Gentile Disadvantage: "Gentiles"; "Uncircumcised", "Without Christ", "Aliens from Israel"; "Strangers from the covenants"; "Without God"; "Having no hope". All of these were Gentile's state before God.
Yet there are examples of believing gentiles within Israel, living among them as brethren... Adopted.
And please DO try to find your 'middle wall' in the Torah. There is no such instruction, beyond the defensive perimeter of the Tabernacle. It is a tradition of men, present in Herod's temple, where the Ark never resided. Folks like to talk about the curtain being torn as signifying access to all to the Holy of Holies - But it also exposed the lie. Part of that lie is the wall of partition.
Here is a Messianic Jewish point of view on the 'wall of partition'.
One must be careful to understand the difference between Torah and Talmudism... Very hard for Christians to do.
I am trying my best to go FROM the BEGINNING to where we are now, but you are trying to mix NOW with THEN, and it won't work. ...clearing throat...2 Tim. 2:15.
Regarding “examples of gentiles living within Israel”. Once again I ask you: there are TWO ways a Gentile could be saved before the wall came down. What are they?
Galatians 3:28 There is neither Jew nor Greek, there is neither bond nor free, there is neither male nor female: for ye are all one in Christ Jesus.
Notice there is a caveat on that no separation. The nation of Israel as well as most of the world are NOT in Christ Jesus. That is what the tribulation period is all about. Those who are not yet in Christ Jesus.