Yahweh's double

1. Most of the agents in OT history are creatures. Men and angels. There are, however, three notable exceptions: Yahweh, the Spirit of Yahweh, and the Angel of Yahweh. 

Now that in itself may not get us all the way to the Trinity, but it sticks out in contrast to the rest. These three agents are categorically different from creatures. 

Not one, or two, or four, but three. So these are the exceptions. In a class apart from human or angelic creatures. 

2. A critic might say the Spirit of Yahweh (in the OT) isn't clearly a distinct person of the Godhead, but an extension of God. God's active presence in the world, or something like that. That's consistent with unitarianism.

However, even if, for argument's sake, we grant that the Spirit of Yahweh isn't clearly a distinct person of the Godhead, the representation of the Spirit is open to a Trinitarian interpretation. 

3. Moreover, it's not as if the Spirit of Yahweh is simply depicted as a power. Among other things, verbal inspiration and propositional revelation have their origin in the Spirit of Yahweh. But communicating words and concepts requires personal agency–from one mind to another. 

4. Then there's the Angel of Yahweh. In Gen 18, there are three "angels" ("messenger", malak), two of whom are creatures, but the third is represented as Yahweh himself. If the third is just another creaturely agent of Yahweh, the differential treatment makes no sense. 

Rather, it's more like a king with his retinue. Compare it to the theophany in Ezk 1. That's not just a theophany, but an angelophany. Not only does God appear to the prophet, but he brings an angelic entourage with him. 

5. There are also debates about whether the Angel of Yahweh is a theophany or Christophany. But for immediate  purposes we don't have to pin that down. The OT needn't present a Trinitarian deity to be incompatible with a unitarian deity. Evidence for binitarian theism would suffice to disprove unitarian theism. Conversely, while evidence for binitarian theism would rule out unitarian theism, it wouldn't rule out Trinitarian theism. Rather, it would mean OT theism is at least binitarian. 

6. If the OT depicted Yahweh as leaving heaven to visit earth (by assuming angelic form), that would be consistent with unitarianism. It would clearly be the same individual. When he's on earth there's no double in heaven. If, on the other hand, Yahweh is shown having a double, then that suggests two distinct individuals: the sender and the sent. And if that's not the case, it's quite confusing (e.g. Gen 24:7,40; Exod 23:20-21; 33:2). 

The point is not whether God has the ability to appear to be in two places at once, but whether that's counterproductive to monotheism if unitarianism is true. Is in the same individual appearing to be in two difference places at once, or two distinct individuals? If Yahweh seems to have a double, how could a reader tell the difference between a unitarian Yahweh and a binitarian Yahweh? 

7. But suppose for argument's sake we say the Angel's identity is ambiguous. The OT is ferociously hostile to idolatry. If unitarianism is true, it's unimaginable that there could be any confusion between Yahweh and the Angel of Yahweh. The very fact that the Angel of Yahweh is sometimes interchangeable with Yahweh (e.g. Gen 48:14-16; Exod 3:1-6) is baffling if unitarianism is true, given the dire OT warnings against idolatry. How could the OT afford to leave that in doubt? If unitarianism is true, then OT representations of Yahweh ought to be consistently and unmistakably monadic, to forestall idolatry.