It's not a presumption to read Romans 11:26 as being
still unfulfilled, for it refers to the salvation of
all of the unsaved elect Jews who will still be alive
at the still-unfulfilled second coming.
(so says you: I disagree)

Paul in 55 AD uses himself as an example of one of the elect of Israel who had been a enemy of the gospel, but who had recieved Christ. In verse 5, Paul sets the tone as "in this present time" there was a remnant of Israel who would be saved.
The future fulfillment of Romans 11:26 does have a
basis in the context of what Paul was writing about
to the first-century Romans, because at that time the
blinded elect Jews hadn't yet been saved (Romans
11:25), but were still enemies of the gospel (Romans
11:28). This was because the fullness of the Gentiles
(Romans 11:25b
Pleroma is in the tense that it has already been being filled.
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During what would have been Jesus' natural 70-year
lifespan, he didn't forgive Israel's sins nor did he
remove ungodliness from Jacob by delivering them from
oppression.
Didn't the believing church escape from the oppression of the Judaizers? Weren't they being persecuted and destroyed by Nero? Didnt' 11 of the 12 (or 13) of the disciples lose their lives under Nero and the judaizers? Didn't the church escape total destruction, just as Jesus said; if the days had not been cut short, no flesh would be saved, but for the sake of the elect, those days were cut short. Nero was ousted.
Instead, in 70 AD he allowed Israel to be
completely destroyed for its sins, and allowed Israel
to be completely oppressed by the Romans for its
ungodliness.
I thought you agreed that Israel is the church. If he didnt' forgive "Israels's sins" the cross is meaningless. Didnt' salvation come to the Jew first? Were'n't all the disciples Jews? What do you mean that he didnt' forgive Israels sins?
The complete installation of the new covenant occurred
at the moment of Jesus' death on the cross (Matthew
26:28, Hebrews 9:15-16), at which moment he also
completely and forever abolished the old covenant
(Ephesians 2:15, Colossians 2:14, Hebrews 7:18-19,
Mark 15:37-38, Hebrews 10:19-23)
.
And since as you say the old covenant has been completely abolished forever and "Israel"
as a nation is an entity that only had a standing with God due to the Old covenant, then Israel as a conditional corporate land/nation entity that was offered in Deut 11-32 had also been abolished forever. Israel as a nation and/or a people have no entity nor covenant with God since the old covenant has been abolished. At least we are agreed with such.
Research when "Israel" was first called a 'people or nation of God". Was it when Israels son's were re-united in Egypt? Was it when they were removed from Egypt by moses? Was it when they recieved the law on Sinaia? No, it was after they were given the conditional covenant to keep all the laws and commands that Moses had given them and the levites and just before crossing the Jordan. Moses told them "this day thou are become a people (of God). Symbolically, the Old covenant began when he brought them by the hand out of Egypt, but the people were not called the people of God until after they had wandered in the wilderness for 40 yrs. (Deut 27:9) "Israel" as a nation of the old covenant land and nation offereing is extinct. The purposes of the geneologies were also over with the fulfillment of the confirmations of the geneologies through the patriarchs.
Yes, today, just as in Pauls day; people of any ethnic group or false religion can come to the full knowledge of the saving Grace of the promised messiah/Creator on an individual level, but there is no more national "Israel" from God's perspective.
However, I disagree with your statement that the New Covenant was fully established at the cross. The "new covenant" included the blessings of Abraham that through Him
all nations of the earth would be blessed. Although the new covnent has its foundation and enforcement from the cross, just as the old covenant was established through a 40 yr process from the leading of the Israelites out of Egypt at passover till the crossing of the Jordan, so also the New covenant of blessings to
all nations of the earth was established and confirmed through a 40 yr process from the cross through the escape of the Israelitish Christians from Judea back across the Jordan to the region of the decapolis while the oppressors of the old covenant (Judaism) were destroyed. Just as Isaiah 59 foretold.
The old covenant ways and hope continued up until the desolation of Jeruslaem and the temple. Just as Jesus said that they should continue in the law until all be fulfilled.
God has inserted a gap of thousands of years to allow
the fullness of the Gentiles to come in (Romans 11:25,
2 Peter 3:8-9).
?????????????? This GAP is what you must believe to support your eschatology and your interpretation of Rom 11. But I do not believe this is what Rom 11 is referring to regardless of how many times you postulate it and offer your opinion. I think as you read your own views about the true church of Christ the Creator being Israel and about the old covenant being fully abolished; AND as you understand that "Israel" that Paul refers to in Rom 11 is sometimes the old covenant 'house' of Israel of the conditional land/nation opportunity and sometimes the spiritual believing "all Israel". you will find some confusing and conflicting ideas that do not support your futurist interpretation of Rom 11.
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Isaiah 59:19b-21 is referring to the same unfulfilled
event as Zechariah 14:2-21, 12:10-14.
And I would say that there is no gap and they were fulfilled. Weather these were fulfilled at the same time or not, I wouldn't' say.
The "so" in Romans 11:26 doesn't mean "in this
manner" in the sense of the jealousy factor way back
in Romans 11:11, but rather in the sense of the
timing factors of Romans 11:25b and Romans 11:26b.
All of the blinded elect Israelite can't be saved
until after the fullness of the Gentiles has come in
(Romans 11:25b) and the second coming of Jesus
(Romans 11:26b) has happened.
"IN this manner" I believe refers to the commentary of Isaiah 59 which I believe had been fulfilled in the first century. We are 'grafted in' to the spiritual laws that were fully enacted and established from the cross through the desolation of the oppressors and the New Covenant of Gods law to Love Him written individually in the Heart.
The original Greek word pleroma (fullness) in Romans
11:25 does mean the fullness of a certain number of
Gentiles getting saved, just as, for example, the
original Greek word pleroo (full) in Acts 7:23 means
the fullness of a certain number of years lived by
Moses at one point in the Old Testament.
Acts 7:23 has the words 40 yrs
tesserakontaetēs to tell us that Pleroo is referring to the completing or filling of the 40 yrs age of moses. In Roman 11 we are not given the word "number" to associate with the filling of "nations". Thus your example of Acts 7 works against you and in favor of the contextual understanding as a spiritual filling and completeness of those individuals in the nations who were recieving Christ. In Romans 9:27 Paul uses the word "number"
arithmos showing that it can be used to indicate a 'number' of people. If Paul would have wanted to say "filled or filling number" he would have written
Pleroma arithmos and would have probably written in the future tense in the words signifying a coming in.
Pleroma (fullness) in Romans 11:12 means a fullness
of the salvation of elect Israel, including a blinded
portion of it which has yet to be saved at the second
coming (Romans 11:25-26).
The fullness of the salvation of elect Israel (Romans
11:12) will be accompanied by the resurrection of the
church (Romans 11:15), for at the second coming will
occur both the fullness of the salvation of elect
Israel (Romans 11:26) and the resurrection of the
church (1 Corinthians 15:22-23,52-53, 1 Thessalonians
4:14-17, Revelation 20:4-6)
.
This is stretching that word too far for even commentary. Read vs 15 where Paul restates and defines through parallelisms what he is referring to in the prior verse. How much more their
fullness is being portrayed and defined as being
"life from the dead" which I think we would both agree is their individual Spiritual life. Again, the corporate land/nation entity of national "israel" is at this time being abolished along with the old covenant; thus this is not referring to a resurrection of a national entity but of individual Israelites in 55 AD yet recieving Christ after they had initially rejected the Gospel message.
Those unsaved individuals who are part of the blinded
portion of elect Israel and who are still alive at
the second coming will all be saved at that time
(Romans 11:25-26, Zechariah 12:10-14) regardless of
what non-Christian religions or atheism they may have
fallen into up to that time, with the exception of the
religion of the Antichrist, no adherents of which
will ever be saved (Revelation 14:9-11).
Again, what is "Israel" if the old covenant has been abolished if we agree that the church is "Israel". Are those people who practice a pagan, Babylonian religion "Israel"?? Isn't all religion that do not believe that Christ has already come in the flesh the religion of the antichrist? (Johns epistles) Isn't Judaism a religion of the "anti-christ" since it rejects Christ as having come in the flesh? Again, your invited to research just who "Israel" was and it's relation to the "old land-nation covenant".
It's a very harmful teaching to give any unsaved
person the idea that he's definitely going to be
saved at some point in the future, because this could
cause him to put off becoming saved today, while he,
if he's elect, still definitely has the chance of
getting saved (2 Corinthians 6:2), and could cause
him to wait so long that he dies unsaved (John 8:24,
Luke 13:3).
And yet this is what your saying will happen to the "unsaved jews" who are reserved to be elected for belief in christ at his 'second coming'.
The "now" in Romans 11:31 isn't carried over into
Romans 11:32, because God won't have mercy on all of
elect Israel until the fullness of the Gentiles has
come in and Jesus Christ has returned (Romans
11:25-26, Zechariah 12:10-14). That's why there's no
"now" in the Textus Receptus of Romans 11:32, and why
there certainly wasn't one in the apostle Paul's
original manuscript of Romans.
It's not vs 32 that is in question. Its the second phrase of vs 31 as underlined below.
vs 30; For as
ye (gentiles of the Roman nations) in times past have not believed God, yet (YE) have
now (40-55 AD) obtained mercy through their unbelief: Even so have
these (55 AD Israelite) also
now (55 AD) not believed, t
hat through your mercy they also may obtain mercy. For God hath concluded them all (both Jew and gentile) in unbelief, that he might have mercy upon all. (all nations, tribes and tongues)
The "they" in vs 31 is referring to the same individuals ("These") who had in 55 AD (NOW) not believed. "Now" doesn't have to be included at the second phrase of vs 31 to understand that the intended individuals were those jews who had initially rejected Christs message but who were elect to recieve mercy through understanding the goodness and fullness of the Gospel of the Creator that was being received by individuals among the Roman nations.
Neither is "might have mercy" in the future tense, but is in the aorist tense.
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Those unsaved people who are part of the blinded
portion of elect Israel aren't destined by election
to believe in Jesus before their death; they'll only
believe in him and get saved if they're still alive
when the fullness of the Gentiles comes in
Pleroma is "that which has completely come in; filled up; or is completely coming in" or 'filling up'. It's not in the future tense. It does not read; "until the full number of the Gentiles
will come in". Again, Pleroma has nothing to do with a number, or else those we think of as "jews" would not be able to recieve christ during this supposed thousands of years Gap. I believe fullness is referring to the fullness of the Spirit of God being recieved by the nations who would then cause some of the elect unbelieving but yet elect of still intact house of Israel of the old covenant.
The context of Pauls message through all of chapter 11 supports this.