The theological category used for [the] interpretation [of Isaiah 53 in the NT] was not primarily that of prophecy and fulfillment. Rather, an analogy was drawn between the redemptive activity of the Isaianic servant and the passion and death of Jesus Christ. The relation was understood "ontologically," that is to say, in terms of its substance, its theological reality. To use classic Christian theological terminology, the distinction is between the "economic" Trinity, God's revelation in the continuum of Israel's history, and the "immanent" Trinity, the ontological manifestation of the triune deity in its eternality. Thus, for example, the epistles of Ephesians and Colossians argue that the creation of the universe cannot be understood apart from the active participation of jesus Christ (C0l. 1:15ff). Or again, the book of Revelation speaks of "the lamb slain before the foundation of the world" (13:8). In a word, in the suffering and death of the servant of Second Isaiah, the self-same divine reality of Jesus Christ was made manifest. The meaning of the Old Testament servant was thus understood theologically in terms of the one divine reality disclosed in Jesus Christ. The morphological fit between Isaiah 53 and the passion of Jesus continues to bear testimony to the common subject matter within the one divine economy. Of course, in a broad sense, isaiah 53 does continue to function as prophecy since the chapter is bracketed within the eschatological framework of an unfolding divine economy.
To summarize, the servant of Isaiah is linked dogmatically to Jesus Christ primarily in terms of its ontology, that is, its substance, and is not simply a future promise of the Old Testament awaiting its New Testament fulfillment. It is significant to observe that in Acts 8, when the eunuch asked about the identity of the Isaianic servant, Philip did not simply identify him with Jesus of Nazareth. Rather, beginning with the scriptures, "he preached to him the good news of Jesus." The suffering servant retains its theological significance within the Christian canon because it is inextricably linked in substance with the gospel of Jesus Christ, who is and always has been the ground of God's salvation of Israel and the world (423).