If dispensationalism - Christian Zionism - were to get rid of its insistence that Old Covenant Israel still exists alongside the Capital C Dispensationalist Church, then it would no longer be the same theology, but a different one. Getting rid of its insistence that Old Covenant Israel still exists would also mean that it gets rid of its postulate that Old Covenant Israel is to be saved as a house sometime in the future and then God will return to a dispensation of works.
The Christian Zionist doctrine that God has two peoples, Old Covenant Israel and the Capital C Church is false because of New Testament scripture in Romans 2: 28-29, Romans 9: 6-8, II Corinthians 3: 7 and 3: 11 and Hebrews 10: 9.
The continuation of Old Covenant Israel depends upon the continuation of the doctrine of the chosen people by the physical bloodline, which Galatians 3:3, 6-9, 16-17,26-29 does not support.
The implication of the postulate that God has two peoples Old Covenant Israel, by the physical bloodline, and the Capital C Church is that both groups are the elect of God, that is, both groups are made up of people all of whom are saved. The New Testament scriptures mentioned above, and more, do not agree with the postulate that all of the physical bloodline are saved under the New Covenant.
The doctrine that the Capital C Church is identical to the Body of Christ and that all in the Capital C Church are of the elect, all are saved, is dependent on an interpretation of Colossians 1: 18 and Colossians 1: 24, that Paul is changing the doctrine of the ekklesia from being only a meeting, assembly or congregation to being the Body of Christ..
In the New Testament ekklesia is used to mean a local assembly of Christians. However in Colossians 1: 18 and in Colossians 1: 24 Paul appears to use ekklesia to mean the body of Christ.
"And he is the head of the body, the church: who is the beginning, the firstborn from the dead; that in all things he might have the preeminence." Colossians 1: 18
"Who now rejoice in my sufferings for you, and fill up that which is behind of the afflictions of Christ in my flesh for his body's sake, which is the church:" Colossians 1: 24
But in Philemon 1: 2, which is a short letter considered to be written at the time of Paul's imprisonment in Rome in about 58 to 62 A.D., Paul used ekklesia to refer to a local church. Philemon 1: 2 says "And to our belived Apphia and Archippus our fellowsoldier, and to the church in thy house."
If Paul in Colossians 1: 18 and 1: 24 intended to change the use of ekklesia from being a local congregation of Christians to being equal to the Body of Christ, the elect of God, he would likely have been consistent in its use in Colossians, Philemon and also in Ephesians. But he uses ekklesia in Colossians 4:15-16 twice to refer to a local assembly. He does use ekklesia in much the same way as he uses it in Colossians 1: 18 and 1: 24 in Ephesians 5: 23, "Christ is the head of the church: and he is the saviour of the body."
Ekklesia, translated a church was used a number of times in the Book of Revelation by John, mostly in Revelation chapters one, two and three, but once in Chapter twenty-two. In Chapters one, two and three ekklesia (church) is always used to refer to a local assembly or congregation.
John Wyclife, of England, translated the first Bible into English in 1382, not from the original languages, but from the Latin. Wyclife translated the Latin word ecclesiam into chirche (in old English spelling):
But then William Tyndale in his 1526 New Testament translated ekklesia as congregation, except for Acts 14: 13 and Acts 19: 37 where he used churche, meaning a pagan place of worship. Tyndale broke with Catholic tradition and used congregation for ekklesia something which might have contributed to his being strangled at the stake by the Catholics.
And after the death of John Calvin, Theodore Beza in 1556 returned to the use of church to translate ekklesia - and the Geneva Bible followed him, using church instead of congregation. Beza returned to the Catholic Capital C Church translation of ekklesia as chirche.
I Peter 5: 2-3 says "Feed the flock of God which is among you, taking the oversight thereof, not by constraint, but willingly; not for filthy lucre, but of a ready mind;
3. Neither as being lords over God's heritage, but being ensamples to the flock."
In the Catholic Church the clergy class ruled over the congregations like "lords over God's heritage," controlling in detail the doctrines followed by the people under them. This is what is meant by the Capital C Church.
Any doctrine is established by the original meaning of the Hebrew or Greek words used to express that doctrine. A translation into English should not change that doctrine. Strong's Exhaustive Concordance defines ekklesia, number 1577, as "a calling out, i.e. (to) a popular meeting, especially a religious congregation..."
The Capital C Church has been given a different meaning than the ekklesia. The Capital C Church has been made equal to the Body of Christ, equal to the elect- almost. The church from ekklesia, has been made into a proper noun. Israel is a proper noun. But ekklesia is a common noun. A proper noun is the name of something that is unique. Israel is unique. A meeting assembly or congregation is not unique.