One problem with Christian Zionist literalist interpretation is that this theology goes back to the Old Testament for its doctrines, which tend to be more physical and literal in nature. Look, for example, at Genesis 17: 10-14 and compare this to Hebrews 11: 8-16.
"And I will make my covenant between me and thee, and will multiply thee exceedingly.
3. And Abram fell on his face: and God talked with him, saying,
4. As for me, behold, my covenant is with thee, and thou shalt be a father of many nations." Genesis 17: 2-4
Genesis 17: 4 says Abraham will be the father of many nations, and the people of the Old Covenant and Christian Zionists following them assumed this meant many peoples or nations would come out of Abraham's physical seed. It turns out that in the New Testament, Abraham was to be the father of a huge number of different nations and peoples through his spiritual seed. See Galatians 3: 16-17, and Galatians 3: 26-29. Christian Zionists cannot hear this.
Continue in Genesis 17: 10-14, "This is my covenant, which ye shall keep, between me and you and thy seed after thee; Every man child among you shall be circumcised.
11. And ye shall circumcise the flesh of your foreskin; and it shall be a token of the covenant betwixt me and you.
12. And he that is eight days old shall be circumcised among you, every man child in your generations, he that is born in the house, or bought with money of any stranger, which is not of thy seed.
13. He that is born in thy house, and he that is bought with thy money, must needs be circumcised: and my covenant shall be in your flesh for an everlasting covenant.
14. And the uncircumcised man child whose flesh of his foreskin is not circumcised, that soul shall be cut off from his people; he hath broken my covenant."
Genesis 17: 10-14 is all about that which is physical or literal, not about spiritual things.
Now look at Hebrews 11: 8-16, "By faith Abraham, when he was called to go out into a place which he should after receive for an inheritance, obeyed; and he went out, not knowing whither he went.
9. By faith he sojourned in the land of promise, as in a strange country, dwelling in tabernacles with Isaac and Jacob, the heirs with him of the same promise:
10. For he looked for a city which hath foundations, whose builder and maker is God.
11. Through faith also Sara herself received strength to conceive seed, and was delivered of a child when she was past age, because she judged him faithful who had promised.
12. Therefore sprang there even of one, and him as good as dead, so many as the stars of the sky in multitude, and as the sand which is by the sea shore innumerable.
13. These all died in faith, not having received the promises, but having seen them afar off, and were persuaded of them, and embraced them, and confessed that they were strangers and pilgrims on the earth.
14. For they that say such things declare plainly that they seek a country.
15. And truly, if they had been mindful of that country from whence they came out, they might have had opportunity to have returned.
16. But now they desire a better country, that is, an heavenly: wherefore God is not ashamed to be called their God: for he hath prepared for them a city."
"By faith he sojourned in the land of promise, as in a strange country, dwelling in tabernacles with Isaac and Jacob, the heirs with him of the same promise:
10. For he looked for a city which hath foundations, whose builder and maker is God."
And, "But now they desire a better country, that is, an heavenly: wherefore God is not ashamed to be called their God: for he hath prepared for them a city."
The New Testament in Galatians 3 and in Hebrews 11 talks about spiritual things, and not physical or literal things. Yet Christian Zionism does not deal with this difference.
An understanding of the promise to Abraham cannot be fully understood by the physical-literal language of Genesis 17, but is more fully understood by the language of Galatians 3: 16-17 and 26-29 and by Hebrews 11, especially Hebrews 11: 9-10 and Hebrews 11: 16.
The New Testament texts, which are not as physical and literal as the text of Genesis 17, gives us a spiritual understanding of the covenant with Abraham which the physical-literalist Old Testament approach alone does not provide.