Reading your post over again, I am really curious about the two views on the nation of Israel and its position in God's plan for salvation (i.e. as the subject of the sentence or as one with Gentiles in Christ Jesus).
Perhaps both views hold to this idea or neither do, but I have always been under the understanding that God chose Israel, set them apart, and gave them the Law to be a light to the world in order draw the world to Himself. Obviously because of their disobedience this did not work as it should have so Christ came into to history to redeem humanity (something I assume He would have had to do anyway since even if we attempt to fully obey the Law, we will always be sinful in our current state and animal blood only points to Christ not actually covering our sins... right?). Wouldn't this mean that while God's promises for Israel will still be upheld, that salvation was always for all humanity (Jew and Gentile) and not just focused on Israel (which is what CD sounds like to me)? Why such the emphasis on Israel?
Why is there such a focus on the Nation of Israel in Dispensational thought? The answer is really quite straightforward, it comes down to their asserted method of biblical interpretation; that is, they follow what they call a Literal method of interpretation. Here is how one of the most famed Dispensationalists, Charles Ryrie, states the classic and/or revised Dispensational approach to biblical interpretation:
Literal Hermeneutics. Dispensationalists claim that their principle of hermeneutics is that of literal interpretation. This means interpretation gives to every word the same meaning it would have in normal usage, whether employed in writing, speaking, or thinking. It is sometimes called the principle of grammatical-historical interpretation since the meaning of each word is determined by grammatical and historical considerations. The principle might also be called normal interpretation since the literal meaning of words is the normal approach to their understanding in all languages. It might also be designated plain interpretation so that no one receives the mistaken notion that the literal principle rules out figures of speech. Symbols, figures of speech, and types are all interpreted plainly in this method, and they are in no way contrary to literal interpretation. After all, the very existence of any meaning for a figure of speech depends on the reality of the literal meaning of the terms involved. Figures often make the meaning plainer, but it is the literal, normal, or plain meaning that they convey to the reader. [Charles C. Ryrie, Dispensationalism, Revised and Expanded, (Chicago: Moody Press, 1995), 80-1]
So when confronted with a passage of Scripture like this:
Or,12 The Lord had said to Abram, “Go from your country, your people and your father’s household to the land I will show you.2 “I will make you into a great nation,
and I will bless you;
I will make your name great,
and you will be a blessing.
3 I will bless those who bless you,
and whoever curses you I will curse;
and all peoples on earth
will be blessed through you. ” ~Genesis 12:1-3 [The 'Abrahamic Covenant']
37 The hand of the Lord was on me, and he brought me out by the Spirit of the Lord and set me in the middle of a valley; it was full of bones. 2 He led me back and forth among them, and I saw a great many bones on the floor of the valley, bones that were very dry. 3 He asked me, “Son of man, can these bones live?”I said, “Sovereign Lord, you alone know. ”4 Then he said to me, “Prophesy to these bones and say to them, ‘Dry bones, hear the word of the Lord! 5 This is what the Sovereign Lord says to these bones: I will make breath enter you, and you will come to life. 6 I will attach tendons to you and make flesh come upon you and cover you with skin; I will put breath in you, and you will come to life. Then you will know that I am the Lord. ’” ~Ezekiel 37:1-6 [The Dry Bones (or 'Nation' of Israel) Vision]Or especially a passage like this:
35 This is what the Lord says,he who appoints the sun
to shine by day,
who decrees the moon and stars
to shine by night,
who stirs up the sea
so that its waves roar —
the Lord Almighty is his name:
36 “Only if these decrees vanish from my sight,”
declares the Lord,
“will Israel ever cease
being a nation before me.”37 This is what the Lord says:
If we are employing a literal method interpretation, as Ryrie describes it; then how else can (must) we take passages like these from the Old Testament? It must be understood as referencing the Nation of Israel as God's prescribed plan for human history; that is, it must be that God has an all encompassing plan for human history that is solely oriented around the Nation of Israel. When you couple this kind of literalist method of interpretation with a Progressive Revelation reading of Scripture (meaning that we start in the Old Testament, and read that into the New Testament); then the natural outcome will be to see the Nation of Israel at the center of prophetic and biblical history.“Only if the heavens above can be measured
and the foundations of the earth below be searched out
will I reject all the descendants of Israel
because of all they have done,”
declares the Lord. ~Jeremiah 31:35-37 [This is right after the famous New Covenant passage, which Dispensationalists believe is only properly understood as applicable to the nation of Israel.]
What is lost in this approach, is an emphasis on Jesus as the the point of Israel's vocation; they were to mediate Yahweh's salvation to the Nations, and it was always understood that the 'Seed' that they carried would be the One to accomplish that purpose for all of humanity (including the Nation of Israel). At least that is what the Apostle Paul thought when he was writing Galatians 3. And yet, I jump ahead of myself; I will touch upon the contrary approach to the Dispensational approach later (and soon).
If I was committed to the philosophy of history, the philosophical assumptions (Scottish Sense Realism), that governs the Dispensational mode of life; then it does make internal sense (relative to their system of interpretation, etc.) that they end up where they do. So the question isn't if Dispensational hermeneutical theory (what informs the way they conceive of doing biblical interpretation) is coherent and self-referentially consistent (within their system); the question is whether or not their system actually best proximates the actual intention of Scripture's message, and salvation history's purpose? I will seek to answer these questions some time soon.
So, do the promises made to the Nation of Israel still stand? I would say yes (again I am jumping ahead of myself, but only to gesture towards answering your questions to me, I will develop my views more later). But qualified in a way that sees Jesus as the ground and fulfillment of what it means to be Israel. The Nation of Israel has the same purpose, in Christ (cf. Eph. 2:11ff) as every other nation. The promises made to Israel are indeed irrevocable (cf. Rom. 11:29), but Israel was always intended to be understood through her ground and purpose and fulfillment, 'in Christ'. This is the key, that is, Christ is the key to sourcing an understanding of a properly constructed 'literal' method of biblical interpretation. The New Testament authors thought so, and thus; so should we. I have left us with quite a few assertions, but this is where I will finally get to as we continue to work through Dispensationalism V. a 'Christ-Conditioned' hermeneutic; for this is where this whole debate really dwells. That is, how it is that we conceive of our philosophies of biblical interpretation? Until next time, brother ...