Hi, I'm new to this site and new to some of the terms used here. I have started a study of Dispensationalism with my pastor. We would term ourselves (although not everyone at my church would--some are much more hard line Dispensationalists) "Progressive Dispensationalists".
In short a Progressive Dispensationalist is a sort of hybrid between CT and DT (if those are the right abbreviations). My general view from my studies is that there are three major covenants that are grant covenants (i.e. not dependent on the recipient). These are the Abrahamic, Davidic, and the New. Each successive covenant reveals more about the prior(s) and about how God intends to fulfill the prior(s).
There are also "already-not yet" versions of these Covenants: Mosaic, Solomonic, To the Seven Churches (this last is mine as I have not heard or read any one else use or suggest this*). These were not grant covenants (Suzerain-Vassal, actually), and are therefore not necessarily eternal.
Anyways (here's my point), I say all of that to say this: the Abrahamic covenant got off to a "rough" start. Ishmael and Esau saw no part of it (other than a large Arab nation). Moreover, Reuben, Simeon, and Levi were all skipped over for the central fulfillment of the covenant as the Messianic lineage passed through Judah. I think that this shows that God will and does fulfill His covenant, but He may not include our particular children.
I think this is also shown in this passage:
John 1:12-13
*I am still studying this and am not yet totally convinced, but I think that it is correct at this point in time. If you know of someone who has taught on this or where I could do more research, then let me know.
Your position is what I believe is called New Covenant Theology (NCT) People such as Wayne Grudem and Fred Zaspel are adherents to this theology. I think it doesn't stand up to classic covenant theology. NCT tries to perpuate a difference between the law of moses (contained in the decalogue) and the law of Christ. In truth, there is no qualitative difference. Christ exegetes his own law, (law of moses) by giving us a fuller understanding of its original intent. Any one else familiar with NCT willing to chime in? It's more of baptist thing.