A280 : by Tony Garland 
The practice of your friends—reading the Church back into the Old Testament—is very common. I think some logical arguments in response to this error have merit. For example: if words have meaning and God doesn't mislead, then the plain reading of Old Testament passages—as understood by the original recipients without aid of the New Testament—must govern their meaning. In other words, what does the Old Testament actually say, especially to those who first received it?
The mystery aspect of the body of Christ, the Church, the "one new man" is also helpful in this regard (Eph. 3:3-6; Col. 1:26-27). For this truth to be a mystery (as the term is used in the New Testament), then it cannot be revealed in the Old Testament. So reading the Church back into the Old Testament is claiming that the Church—the body of Christ— is not a mystery: in that it was revealed, in some limited form, in the Old Testament. Thus, this practice of finding the Church in the Old Testament violates Paul’s teaching that it was never before revealed in God’s Word—whether subject to illumination or not.
You asked, if the everlasting "covenant of peace" with Israel in Ezekiel 37:26 refers to the New Covenant, would that mean that there is more to the New Covenant than what Jesus did on the cross?
I would answer, “yes and no.” 
Yes: in that the New Covenant serves as the capstone of all the other "eternal" covenants (Abrahamic, Davidic) and supplants the Mosaic—and serves as the means by which they are brought to fruition. So the cross makes possible the promises of those earlier covenants which point toward the cross. For example, when reading the Abrahamic Covenant (Genesis 12; 15) one can see how it is fulfilled by the work of Jesus on the cross (and that we are "sons of Abraham" by faith (Gal. 3:7)—which is how we, as "families of the earth" are blessed with salvation). Yet that same Abrahamic Covenant is also the root of the land promise to Israel—which does not apply to the world-wide church.
No: in that there is nothing that the New Covenant deals with or accomplishes that does not depend absolutely entirely on the cross-work of Jesus. For example, when we look at conditional aspects of the Abrahamic Covenant (possession of the promised land) and the Davidic Covenant (occupation of the throne), the conditions require the obedience of Israel. How is that obedience going to come about? Through the conversion of Israel based upon the New Covenant (e.g., Jeremiah 31:31-34; Romans 11:25).
So it depends on what one has in view when one says, "what Jesus did on the cross."
If one means by this statement: personal salvation, gaining heaven, eternal life, then I supposed you can say "yes there is more to the New Covenant." On the other hand, if one means: all the streams of promise and covenantal aspects predicted in the Old Testament, then I think we have to say "no" because the cross-work is foundational to bringing all these aspects to fruition in God's plan. So there is a sense where the new covenant is "not just another covenant," it is THE covenant of covenants, as-it-were. It is the capstone of God's covenantal program with both mankind and the nation of Israel.
Most of the Old Testament focuses on the "Israelitish" aspects of it (e.g., Jer. 31:31, Ezekiel 37), but even some places in the Old Testament reveal the larger scope—although not necessarily using the term "New Covenant (e.g., Genesis 12; Isaiah 53). When we get to the New Testament, progressive revelation fills in aspects that were not revealed in the Old Testament—primarily in relation to the mystery of the Church and its participation (which is completely absent from a plain reading of Jer. 31:31 and following).
You asked, are there more political and geographical components to the New Covenant than spiritual salvation?
If your question, is [there] more to the New Covenant than what Jesus did on the cross is understood as having in view spiritual salvation, then the answer is, "yes." But I would argue that such a view of his cross work, as popular and common as it might be due to our tendency not be as familiar with the full corpus of Scripture, is too limited.
The cross accomplished much more—and not just in relation to Israel. For example: the redemption/restoration of creation itself (Romans 8:20-22). The work on the cross eventually puts right all that is wrong—every aspect of the Fall and its consequences.
Also, although it may seem like picking nits, I feel the phrase double (or multiple) reference is a more precise way to describe the phenomenon which is often referred to as double fulfillment.
When a passage or phrase in Scripture takes in more than one historical end-point, the passage generally contains a mix of both elements—not so much having both in view in the same words and occurring twice. Be that as it may, I can see where you are going in that God promising to dwell in a temple within Israel's midst forever in Ezekiel which has much in common with Spirit baptism and the formation of the Church, the body of Christ.
Here's the key: in order for a passage in the Old Testament to "refer" to a New Testament truth, the New Testament truth must be evident in the plain meaning of the Old Testament passage (without aid of the New Testament).
In our example here, I don't think anyone reading the end of Ezekiel 37, without the aid of the New Testament, would ever come away with the idea of God's Spirit indwelling people (rather than a building). More than that, if we were somehow to find this idea in the passage, it would undermine the literal sense which is actually pointing to a physical temple in the millennium (which will be Ezekiel's subject in 3 more chapters!). So we can't find the New Testament temple revealed in the passage and we mustn't detach the promise from a physical building which the passage is really on about.
But, as you've pointed out, it would be silly to ignore the similarity between Ezekiel's passage and what we know the New Testament reveals about the temple of the believer/Church—after all, why else would Paul cite Ezekiel’s passage? So what are we to do?
This is the topic of "typology" in which something earlier in Scripture points toward or hints at something which has a fuller expression later in Scripture (Col. 2:17; Heb. 8:5; 10:1). There is not a one-to-one correspondence as with prediction and fulfillment, but it is clear, in hindsight, that what went before is purposefully related in various ways to what is revealed later. So, for example, God's presence dwelling within the Holy of Holies in the physical temple "points toward" or "sets the stage for" God's indwelling the believer as the Holy Spirit. In this case, Ezekiel's promise that God will eventually return to a physical temple in Israel's midst (after having recently left the physical temple a number of chapters earlier) has a physical (literal) fulfillment following the conversion of the Jews at the return of Jesus: in the millennial temple. The same passage in Ezekiel can also be said to function as "a type" (a model) of the New Testament temple comprised of believers indwelt by God's Spirit. In the former case, it is a prediction/fulfillment relation where what is plainly predicted/understood actually comes about in the same/expected way. In the latter case, what comes later would not have been discerned from the earlier, but in retrospect the two have much in common and share spiritual truths (e.g., a temple is where God fellowships with sinful man by means of a mitigating atonement).
In my view, Paul's reference to this passage from 2 Corinthians relates to typological use where he is revealing that the New Testament temple of the believer is patterned after what the Old Testament reveals about the physical temple. He's not expecting anyone to have read the end of Ezekiel 37 and taken it as a prediction of the New Testament temple.
You state, If what Paul referred to in 2 Cor 6:16 was not a fulfillment but merely a picture, then that would mean that the actual fulfillment of the New Covenant (where He dwells in the idea of His tabernacle and sanctuary and dwelling place being in their midst) hasn't happened, and there's a lot more to the New Covenant than the cross and spiritual salvation and there's a separate Jewish aspect to that specific covenant that we are not involved in.
Yes! You've got it
The New Covenant contains numerous aspects which are not often appreciated, mostly things which are stated in the Old Testament and not as familiar. This is another reason why folks like me are constantly on about the millennial kingdom: because one of the reasons for that period of time is to bring to fulfillment the many things related to the covenants—which ultimately find their means of fruition in the New Covenant. But rather than saying, "there's a lot more to the New Covenant than the cross and spiritual salvation," I would prefer to say, "there's a lot more to the cross than spiritual salvation." Indeed: all those things which are associated with the New Covenant.
It's not so much that the New Covenant goes beyond the cross, but that the cross goes beyond the common understanding of what it accomplished. This can be seen in careful consideration of what Jesus said on the night of His betrayal, "This cup is the New Covenant in My blood, which is shed for you." By connecting His shed blood on the cross with the "New Covenant," He is underscoring that His work on the cross includes much more than the redemption of individuals—including all those things which other passages concerning this covenant reveal from the Old Testament. Much of the Book of Revelation (focusing especially on opening the scrolls from chapter 5 onward) also deal with this larger scope of redeeming/restoring that which has been lost.
Lastly, I would emphasize that this is not a simple area of study. There are numerous subtle aspects to wrestle with. So much so that it has even caused some interpreters (thankfully the minority) to conclude there must be TWO new covenants: one for Israel and one for the Church!
A much better solution, in my view, is to hold to a single covenant which is the apex of God's redemptive/restorative work and which is the subject of progressive revelation. Since the Church is a mystery not revealed in the Old Testament, we shouldn’t expect—nor do we see—mention of its role in relation to the New Covenant within the Old Testament. Once we get to the New Testament, the mystery begins to be revealed, and what was said concerning the New Covenant in the Old Testament—and especially its seeming exclusively Jewish aspects—is augmented (but never subverted or reinterpreted) and we get a more complete picture.
Much confusion abounds.
Since only the non-Church aspects are revealed in the Old Testament, but the Church is obviously party to the New Covenant in the New Testament (Mat. 26:28; Mark 14:24; Luke 22:20; 1Cor. 11:25; 2Cor. 3:6; Heb. 9:15; 10:29; 12:24), it causes people to erroneously "pour" the Church back into the Old Testament, most often by taking "Israel" as the "people of God of all ages" or the "Church" as the "New Israel."
Then there is the other camp which, because the Church isn't mentioned in the New Covenant passages in the Old Testament, conclude that the Church does not participate in the New Covenant which, they conclude, must be exclusively Jewish. But I think that's a pretty tough sell given the words of Jesus at the Last Supper (and communion being an ordinance of the Church) as well as Paul's statement that we are "ministers of the New Covenant" (2Cor. 3:6). Seems tough to "minister" something we don't have! (Let's see: we are ministering the New Covenant which provides for individual salvation, but we ourselves don't participate in it?!!! Egads!)
In my view, both sides share in the same error: they are not properly accounting for the nature of progressive revelation in light of the Church being a mystery. If Israel and the Church are both beneficiaries of the New Covenant, then we shouldn't go looking for the Church in the Old Testament (an unrevealed mystery) nor should we change "Israel" in the Old Testament to mean "Church." We let the words mean what they say on both sides and understand how progressive revelation broadens the scope of the New Covenant, especially in relation to the unrevealed "body of Christ," as we pass from Old Testament to New Testament. | 
