In my view much work on New Testament christology has employed categories of thought that are certainly no less appropriate than those of the patristic definitions. In particular, much damage has been done by the standard distinction between functional christology and ontic christology. The former means that Jesus performs divine functions (such as saving and judging) but only as an agent of God, while ontic christology goes further in claiming that Jesus shares the being of God or is divine by nature. A widespread assumption has been that in the Jewish monotheistic context in which the earliest christology developed only functional christology is conceivable. Ontic christology is possible only to the extent that early Christianity moved outside a dominantly Jewish framework of thought, and the more scholars have come to think that most, if not all of the New Testament writings belong within a Jewish framework of thought, the more ontic christology has been pushed to the margins of the New Testament. There has been a strong tendency to read New Testament christological texts in as 'low' a way as possible on the grounds that their original Jewish context requires this. Obviously, the gap between the Christ of the New Testament and the Christ of later patristic orthodoxy grows deeper and wider.
While I entirely agree that Jewish monotheism was the context of thought within which early christology originated and developed, I think that the relationship of early christology and Jewish monotheism has been profoundly misunderstood. It is vital to work with categories that are appropriate to the texts we are considering, and it seems to me that the category most helpful for characterizing both Jewish monotheism and New Testament christology is that of divine identity. Jewish theology was much more concerned with 'who God is' (divine identity) than with 'what divinity is' (divine nature). Jewish monotheism defined the unique identity of God - what it is that constitutes God the only God - in a number of ways, of which the most prominent are that the God of Israel is the only creator of all things and the only sovereign ruler of all things. These were ways of distinguishing the one God absolutely from all other reality. The exclusive worship of only this one God was the appropriate way of recognizing his unique identity. When we read the New Testament with these ways of characterizing the unique identity of the God of Israel in view, it becomes very clear that the New Testament writings use precisely these uniquely divine characteristics to include Jesus within the unique identity of the God of Israel. When Jesus is pictured as seated at God's right hand on the cosmic throne in heaven from which God exercises his sovereign rule over all things, Jesus is being included in the unique divine identity. It is not that Jesus is exercising a divine function which God may delegate to someone other than God. Sovereignty over all things is a uniquely divine relationship to the world and belongs to who God is. Similarly, and even more unambiguously, when the New Testament portrays the pre-existent Christ participating in God's work of Creation, there could be no clearer way, in Jewish theological terms, of claiming that Jesus belongs - eternally - to the unique identity of the one God, the God of Israel, the Creator and Ruler of all things. This is why early Christians worshipped Jesus without supposing that they were abandoning Jewish monotheism. In terms of the definition of Jewish monotheism, the worship of Jesus as included in the unique divine identity made sense, whereas the worship of Jesus as someone other than God, to whom God merely delegated divine functions, would have been idolatry and effectively polytheism. Early Christianity remained monotheistic precise because it attributed divinity in the fullest (and only true) sense to Jesus, not because it made Jesus some kind of lesser divinity distinguished from God.
From this perspective all christology in the New Testament is equally 'high' since at least Jesus' status as exalted to the divine throne of the universe - the symbol of God's uniqueness - is everywhere presupposed and in this basic sense the New Testament writings share a common christology. Against the background of twentieth-century study of New Testament christology, I find rather astonishing to be able to say that, from Pentecost onwards, there was never a stage at which Christians did not consider Jesus to share in the unique divine identity, but I think this is true. In the New Testament there is christological development in the sense of drawing out the implications of this, but there is no development from 'low' to 'high' christology. New Testament christology is already the highest possible christology - but developed and expounded in Jewish theological terms. What made the difference for the Fathers was, first, a context in Hellenistic philosophy which highlighted divine nature rather than divine identity, and, secondly, the temptation to understand monotheism in a non-Jewish way, such that the uniqueness of the one God (the Father) could be maintained by attributing subordinate divinity to Christ. These problems required the Fathers to work through the issues of trinitarian and christological doctrine in order to reach definitions that adequately re-stated the claims of New Testament christology in a different intellectual context. These definitions are Hellenistic insofar as they give prominence to notions of divine and human nature (what it is to be divine, what it is to be human), but they also correspond to the New Testament's Jewish thinking about God insofar as the idea of divine nature is subordinated to a trinitarian understanding of God and a hypostatic (personal) understanding of incarnation. The Trinity is the Christian statement of God's identity (who God is) and the statement that the eternal divine Son made human nature his own in incarnation effectively includes the man Jesus within the identity of the one and only God.