The OT speaks of the "Angel of the Lord" in many different places, including one of the three angels that visited Abraham, the burning bush, in Isaiah's and Jeremiah's visions. I have heard it argued that this "Angel of the Lord" was the pre-incarnated Lord Jesus. Do you believe this? What scriptural evidence do you have for or against?
I've lately thought that this was the incarnate, ascended LORD Jesus. He, being in Eternity since the Ascension, is the Master of Time and Space, and is able to appear when and where He pleases. This is how I see Isaiah 6, when the LORD Himself spoke to Isaiah and 'stretched forth His hand', among other things. A pre-incarnate Angel (messenger) of the LORD does not "sit" upon a physical throne. Then again, in Gen. 15 the three Angels? appear before Abraham outside Sodom & Gomorrah, and he falls down and worships. All three cannot "be" the Blessed Trinity, as only the Son has any physical expression. The Spirit was only ever "like" a Dove.
Most (maybe all?) of the "Angel of the Lord" instances in the OT do seem to be the Lord himself. Most scholars that I've read argue for the pre-incarnate Christ explanation, just as they do with the Commander of the army of the Lord in Joshua. Appearing as a man is certainly something that God could do if he chose to do so. He also appeared as a pillar of fire and cloud, after all. He spoke from a burning bush. These theophanies are distinct from the Incarnation, and there's no reason why appearing as a man would be any different. These events could have been the Son. I think that there are certain risks involved with trying to determine which Person of God was present. He's as much one as he is three, and as much three as he is one. It could have been any of them, it could have been all of them. It is consistent with the nature of the Son for it to have been a pre-incarnate Christ, but I don't know if we can be certain. It was God manifest among them, though.