From a discussion held elsewhere:
The COG paradigm is not going to be found in NC thinking. Though there are of course gracious elements to the Old Covenant…that Covenant itself wouldn’t be seen as gracious, as is the New Covenant. OC is per Code (Do this and live!). NC is per Christ (Having done this that we might live!).
The driving force behind NC thinking is “Christ as the unity of all redemption and revelation.” This makes the idea of “covenant” to be something other than a primary motif, though it certainly factors into the role of Christ as hermeneutical key.
Unity is thought to be in Christ himself, filling up and fulfilling all covenants leading unto the Incarnation. Essentially, Christ is understood to be the incarnation of all that the OC Law demands and OC Prophets promise. Hence, typologically speaking, Christ is the link between the OC covenants as they unfold throughout the OT.
All OC typological (ectypal) realities are subsumed in Christ, the archetypal reality.
Christ would be understood as the colligate of all redemption and revelation, and not a theological category of ‘covenant of grace’.