"until" the fullness of the gentiles come in.
Read these verses in the same passage and see if you can explain the meaning of the word "fullness":
Now if the fall of them be the riches of the world, and the diminishing of them the riches of the Gentiles;
how much more their "the fulness" [G4138 pleroma]? (Rom.11:12).
The word is preceded by the definite article:
"the fulness", and this is what it means:
4138 πλήρωμα plhvrwma pleroma {play'-ro-mah}
from 4137;
repletion or completion, i.e. (subjectively) what fills (as contents, supplement, copiousness, multitude), or (objectively) what is filled (as container, performance, period):--which is put in to fill up, piece that filled up, fulfilling, full, fulness. see GREEK for 4137
4137 πληρόω plhrovw pleroo {play-ro'-o}
from 4134;
to make replete, i.e. (literally) to cram (a net), level up (a hollow), or (figuratively) to furnish (or imbue, diffuse, influence), satisfy, execute (an office), finish (a period or task), verify (or coincide with a prediction), etc.:--accomplish, X after, (be) complete, end, expire, fill (up), fulfil, (be, make) full (come), fully preach, perfect, supply.
It's a fullness of supply of grace being spoken about - and
it's the same word being used for "the fullness of the Gentiles".
For I would not, brethren, that ye should be ignorant of this mystery, lest ye should be wise in your own conceits; that blindness in part is happened to Israel, until the fulness of the Gentiles be come in. (Romans 11:25).
Paul is saying that part of Israel has been blinded until this period of grace is up. "Until the fulness of the Gentiles be come in"
means the time for the supply of grace through the faith in the gospel of Christ has a limit - and Paul states that DURING THE SAME PERIOD the Jews
who do not persist in unbelief will be grafted back into the Olive tree (Rom.11:23).
This is the only period of grace, brother. Stop bluffing yourself with false theology.
When Paul says "As concerning the gospel,
they are enemies for your sakes" (Romans 11:28a)
he is still talking about the natural branches who became enemies and were broken off, who he began talking about at the beginning of the chapter;
and when he says
"but as touching the election, they are beloved for the fathers’ sakes." (Romans 11:28)
he is still talking about the elect remnant who he began talking about at the beginning of the chapter, i.e
the remnant of the natural branches - those same natural branches of the olive tree (Israel)
with whom we Gentiles who have been grafted in, share in the root and fatness of the olive tree.
The above is the only thing Paul means when he says
"And so all Israel shall be saved" because then he quotes the prophecy regarding Jesus:
as it is written, There shall come out of Sion the Deliverer, and shall turn away ungodliness from Jacob:
For this is my covenant unto them, when I shall take away their sins." (Romans 11:26-27).
He is talking about the one and only covenant in the blood of Christ that has taken away OUR sins (Israel -
all the branches of the olive tree - the remnant of the natural branches + unnatural branches grafted in). Our Deliverer came out of Zion nearly 2,000 years ago.
You are bluffing yourself and have bluffed yourself into believing there is a second period of grace following the return of Christ during which "the Jews who had remained broken off" will receive grace.
The unbelievers who grumbled in the wilderness all perished in the wilderness. They did not enter the promised land. This period of grace
is what the author of Hebrews calls "Today" when he writes to the Jews:
"While it is said, Today if ye will hear his voice, harden not your hearts, as in the provocation. For some, when they had heard, did provoke: howbeit
not all that came out of Egypt by Moses. But with whom was he grieved forty years?
was it not with them that had sinned, whose carcases fell in the wilderness? And
to whom sware he that they should not enter into his rest, but to them that believed not?
So we see that they could not enter in because of unbelief." (Hebrews 3:15-19).
This is why Paul wrote to the Romans saying, "And they also,
IF they abide not still in unbelief, shall be graffed in: for God is able to graff them in again. For if thou wert cut out of the olive tree which is wild by nature, and wert graffed contrary to nature into a good olive tree: how much more shall these, which be the natural branches, be graffed into their own olive tree?" (Romans 11:23-24).
But once this period of the fulness of (supply of) grace is over, it's over.
Stop bluffing yourself. The fullness Paul is talking about has nothing to do with a number (of Gentiles that must be repleted). It's talking about the fullness of the grace of God, the fullness supplied by God by His grace.