Is an Incarnation alien to Judaism?

1. There's often thought to be an awkward hiatus between OT messianism and NT Christology. The deity of Christ is broadly attested in the NT, which is Jewish, yet it's often felt that the deity of the messiah is thinly attested in the OT. 

2. Elucidating the divine messiah from the OT generally involves a few key prooftexts as well as the Angel of the Lord. In addition, it's commonly argued that the revelation of the Trinity was a two-stage process. To stamp out polytheism, it was initially necessary to accentuate monotheism before it was safe to more explicitly reveal the Trinity.

3. I think all those explanations are good up to a point, although it's too limited. In the past, I've argued that there are two additional strategies that provide broader platforms:

i) There's a pervasive Yahweh-is-coming motif in the OT. The question that raises is whether Yahweh ever actually comes. Does Yahweh always only come in the indirect sense that his coming is mediated through agents and events? Or are these intermediaries preparatory for a personal advent of Yahweh himself?

ii) In addition, there's a royal sonship motif where messiah is the heir of God's kingdom. But typically, the crown prince is on the same level as the king. In what sense is a human being the successor or coregent of God himself? 

4. However, now I'd like to approach this from another angle. There's no disjunction between OT and NT theism. To the contrary, Yahweh is the only kind of Deity who could become Incarnate. OT monotheism is a necessary precondition for the possibility of divine incarnation.

In philosophical theology, much is written about the possibility or impossibility of a divine incarnation. What needs to receive greater attention is that certain kinds of beings cannot become incarnate, even in principle. 

The foil for OT monotheism is pagan polytheism. However, even if heathen deities existed, it would not be possible for them to become incarnate. The reason is twofold: 

i) Heathen deities are physical to begin with.

ii) Heathen deities are already humanoid.

The possibility of a divine incarnation requires a point of contrast. If a deity is too similar to creatures, too similar to human beings, then it cannot assume that nature or relation.

For instance, how could Zeus become incarnate? He's already a physical being. And he already has a humanoid mind, humanoid passions. 

The Incarnation is often thought to be difficult or paradoxical because divine and human natures are so different from each other. Yet that objection has it backwards. Their dissimilarity is what makes a union meaningful. For union involves distinction. If two things are already the same kind of thing, or highly analogous, then there's no real change in the sense of what differentiates union from the absence of union.

Take science fiction stories about intelligent aliens who engage in body-swapping. They transfer their minds to human bodies.

But that's not an incarnation. That's possession. An alien mind takes the place of a human mind. And the alien trades its indigenous body for a human body. Yet the alien, in its natural state, was already humanoid. It has humanoid intelligence and a physical body. 

Compare that to Christology, which involves the person of the Son in union with a human body and rational soul. It's because the two natures are unlike that there's a qualitative difference between an incarnation and no incarnation. 

In the case of Yahweh, there's a difference of kind rather than degree. Yahweh is not a physical being. And he doesn't have the psychological makeup of a human being. Just compare him to Zeus. 

It's because OT theism clearly distinguishes the true nature of deity from humanity and pagan divinity alike that it provides the necessary backdrop for a divine incarnation. An incarnation is impossible if there's already too much preexisting continuity between the Deity and what he assumes. 

The difference between Zeus and Odysseus is quantitative rather than quantitative. As such, they are too alike at the outset for a union to represent something fundamentally different from what they are apart from union.