Showing posts with label The Trinity. Show all posts
Showing posts with label The Trinity. Show all posts

Sunday, January 05, 2025

Did prayer to saints and angels develop in a way comparable to the development of the canon?

When the historical evidence against a Roman Catholic belief is brought up, a common Catholic response is to compare the development of that belief to the development of the canon of scripture or Trinitarianism. Here's something I recently posted in a YouTube thread about the subject. YouTube has had a problem for years with some people's posts sometimes not appearing. Many of my posts don't appear after I submit them, and I still haven't found a way to determine which posts will go through and which won't. The one below didn't go up. Here's a link to the YouTube comment I was responding to. You can read that comment and the surrounding context if you want more information about what led up to my response below.

Tuesday, June 25, 2024

The Historicity Of The "I Am" Statements Of Jesus

Critics often object to the historicity of the gospel of John on the basis of the presence of "I am" statements of Jesus there that aren't found in the Synoptics ("I am the light of the world", "I am the good shepherd", etc.). Whether such statements are absent from the Synoptics is a disputed issue, but to whatever extent they are, their presence in John is much less problematic than is typically suggested. We don't need to know why the statements weren't included in the Synoptics in order to have sufficient reason to believe in the historicity of the statements. But it's easier than critics suggest to explain why the "I am" statements would be absent from the Synoptics if the statements were made by Jesus.

Thursday, January 19, 2023

A Multipersonal God In Genesis

Than Christopoulos recently posted a good video about the Angel of the Lord in Genesis. And here's another video he recently did with Caleb Jackson about a healing of stomach paralysis with medical documentation.

Sunday, January 08, 2023

Isaiah 9 Resources

The first seven verses of Isaiah 9 are highly significant, but usually underestimated, in a lot of important contexts. They have implications for Jesus' identity, how he viewed himself, who he claimed to be, how he was perceived early on, the continuity between the gospels' accounts of his childhood and their accounts of his adulthood, some prophecy fulfillments that are highly evidential, and other significant issues. I've written many posts on Isaiah 9 over the years, and I want to produce a collection of links to some of those posts, so that they can be accessed more easily in one place. I expect to update this post periodically when warranted.

Wednesday, February 23, 2022

Tuesday, March 09, 2021

A Good Discussion Of First Clement

James White recently had a good discussion with Stephen Boyce about First Clement. They talk about the letter's significance with regard to Trinitarianism, the canon of scripture, justification, church government, and other subjects.

Tuesday, December 15, 2020

Pete Enns Is Wrong About Isaiah 9

See his article here. He's wrong about what Isaiah 9 refers to in its original context, and he's wrong about how the earliest Christians viewed the passage. On the original context, see here and here. On how the earliest Christians understood the passage, see here and my other posts since then that discuss the issues further.

The fact that Isaiah 9 opens with an eighth-century B.C. backdrop doesn't suggest that the entire passage will be fulfilled at that time or shortly after. It can be relevant to an eighth-century B.C. audience and be sufficiently understood by them without being entirely fulfilled at that time or shortly after and without being entirely understood by that initial audience. Jesus' fulfillment of the passage centuries later, without any fulfillment by Hezekiah or somebody else earlier, doesn't mean that the passage has "no relevance to Isaiah’s audience", as Enns claims. It has a lot of relevance, much as unfulfilled eschatology and other types of predictions not yet fulfilled have a lot of relevance to modern Christians.

Enns writes that "It is striking, though, that Matthew doesn’t go on and cite the rest of Isaiah 9, especially verses 6-7". He doesn't need to. It would be absurd to think that Jesus is the figure of the first two verses of the passage, but that verses 6-7 refer to somebody else. Verse 7 refers to David's throne. Jesus' Davidic Messiahship is a major theme in Matthew's gospel. It would be ridiculous to suggest that he thought Isaiah 9:6-7 refers to somebody other than Jesus. Similarly, Jesus only needs to cite a portion of Psalm 22 in order to suggest that the whole Psalm applies to him (Matthew 27:46).

Enns goes on to tell us that Matthew "is only one of two New Testament writers who bother to even tell us about Jesus’s birth". See here regarding the material on Jesus' childhood outside of Matthew and Luke. John's gospel, for example, tells us a substantial amount about Jesus' childhood, including his fulfillment of Isaiah 9. And notice that Jesus' appeal to the opening verses of Isaiah 9 in John 8:12 comes in the context of responding to allegations about issues like his ancestry and birthplace (John 7:41-42, 7:52), which implies that Jesus is intending to appeal to the Isaiah 9 passage as a whole, not just the opening verses. The closing verses of the Isaiah 9 passage, not the opening ones, are the verses that refer to birth and Davidic ancestry (with the implication of a Bethlehem birthplace, for reasons I've gone into elsewhere). The evidence suggests, then, that Jesus is applying the Isaiah 9 passage as a whole to himself in John 8:12. So, Enns' claim that "Connecting Isaiah 9 to Jesus was the work of later church theologians" is false.

Sunday, August 16, 2020

Principles For Evaluating Development Of Doctrine

The subject of doctrinal development often comes up in discussions with Roman Catholics, but it's relevant to other contexts as well. We've written a lot about it over the years, and you can find many relevant posts in our archives. I want to outline several of the principles we should keep in mind as we think about the topic:

- Different individuals and groups make different claims about the beliefs under consideration, and they bear different burdens of proof accordingly. Catholics can't try to have the benefits of making higher claims about the alleged history of their doctrines without also paying the cost of bearing a higher burden of proof. The two go together. See the second-to-last paragraph of the post here regarding what Roman Catholicism has claimed about the history of the assumption of Mary or the opening paragraphs here regarding the papacy, for example.

Friday, August 07, 2020

Soteriology As Evidence For The Gospels

A neglected line of evidence for the harmony and historicity of the gospels is their agreement on soteriological issues. I'll cite several examples.

They all approach salvation from a first-century Jewish perspective, as a matter of needing to be reconciled to the God of Israel because of our sin. In all four gospels, Jesus doesn't just lead people to God the Father, but also calls them to himself to an extent unprecedented among the prophets, priests, kings, and other earlier leaders and later church leaders: come to him, believe in him, follow him, he forgives sins, etc. Salvation is framed in terms of being Abraham's children in a spiritual rather than physical sense (Matthew 3:9, Luke 19:9, John 8:39). The redeemed are referred to as children in a broader sense as well, without the connection to Abraham, and as young children in particular (Matthew 18:3, Mark 10:14, Luke 11:13, John 13:33). Salvation involves entrance into the kingdom of God (Matthew 5:20, Mark 10:15, Luke 18:24, John 3:5). All of the gospels portray Jesus' crucifixion as salvific, as illustrated by the Last Supper and Jesus' comments in John 6, for example. There's a common theme of Jesus as the shepherd who lays down his life for the sheep (Matthew 26:31, Mark 14:27, Luke 15:4, John 10:11). All of the gospels agree on the freeness of salvation, in the sense that it's received through faith alone, as illustrated in my recent post on justification apart from baptism. All four gospels portray repentance as implied by faith, so that repentance will sometimes be mentioned alongside faith to emphasize it, whereas only one or the other will be mentioned on other occasions. They agree in having faith accompanied by regeneration and sanctification, so that saving faith is evidenced by improved behavior. Matthew 11:28-30 has Jesus offering rest and a yoke simultaneously. John 5:24 lays out justification through faith alone, then follows it with a reference to judgment according to works in 5:29. And the gospels agree about the general parameters of the connection between faith and works. Jesus demands perfection (Matthew 5:48, Mark 12:28-31, Luke 6:36, John 15:12), and there are comments about how "difficult", "impossible", etc. his demands are (Matthew 25:24-26, Mark 10:17-27, Luke 18:18-27, John 6:60), yet those demands are accompanied by his acceptance of individuals who fall well short of what he's demanding. Men like Peter and John are portrayed as redeemed individuals and different than the average person (having faith, associating closely with Jesus, etc.), but they still sin to a significant degree. There's also agreement that individuals like Judas were never saved to begin with. People often associate the thinking behind 1 John 2:19 with the fourth gospel, but some of the same concepts are found in Matthew 7:21-23.

To appreciate the importance of agreements like these, consider how easily the gospels could have disagreed, even disagreed radically, on these matters. Think of the wide variety of views of salvation of one sort or another found in Buddhism, Islam, Judaism, Christianity, etc. To cite an example I discussed in another recent post, think about the role of baptism in the gospels. Given the tendency in Christian circles to make baptism more prominent in later centuries, it would have been easy for one or more of the gospels to have given baptism a much more prominent role if the gospels had been written later and were less historical.

Monday, July 13, 2020

Nothing Is More Pragmatic Than Theology

In my daily reading of scripture, I recently came to chapter 7 in Matthew's gospel, where the section commonly referred to as the Sermon on the Mount ends. It's striking how Jesus' remarks close with his referring to the significance of the afterlife (7:21), himself as mankind's judge, who judges based on people's relationship with him (7:23), and his words as foundational to life (7:24). Matthew highlights how the crowd was impressed by his authority (7:29), not something like his sincerity, emotions, or love.

Modern culture typically gives far more attention to some of Jesus' earlier comments, such as what he said about peacemakers (5:9) and loving your enemies (5:44). There are many comments Jesus makes earlier in the Sermon on the Mount about God, the afterlife, and such, which often get ignored or underestimated, but the closing remarks of chapter 7 are especially striking.

One reason that's often given for placing so much focus on things like peacemaking and loving your enemies (often defined in highly anti-Biblical ways that Jesus would have opposed) is that such teachings are so pragmatic. By contrast, teachings about God, salvation, prayer, the afterlife, and such allegedly are far less practical, if they're practical at all. The same individuals who put so much emphasis on what Jesus said about loving people often ignore or give little attention to what Jesus said about how loving God is more important (Matthew 22:37-39). While modern culture has such inordinate concern about short-term physical welfare (giving people food, clothing, shelter, and medicine; helping them find a job; sexual pleasures, humor, and such), Jesus tells people to be prepared to give up something like an eye or a hand for welfare in the afterlife (Matthew 5:29-30, 18:8-9). I wrote the following about this subject on Facebook a few years ago:

Nothing is more pragmatic than theology. I recently had a conversation with a friend whose mother-in-law is dying. He's concerned that his mother-in-law, who comes from a Roman Catholic background, have the peace, comfort, joy, and other advantages of knowing that she's going to heaven rather than purgatory. But how many people are concerned enough about a subject like purgatory to research it to any significant extent before they get close to death? Our culture encourages us to not have much concern about theology in general, and, more specifically, it's often suggested, even by Christian leaders, that the differences between Catholics and Protestants don't matter much. Would they hold the same view on their deathbed, when the difference between heaven and purgatory is staring them in the face? Or would they tell a dying parent or friend to not be concerned about the issue? What if their child were to start praying to the dead? Would they be as unconcerned about the subject as they are now, when they're addressing it at a more abstract level? Theology is foundational to everything from the reliability of our reasoning to our purpose in life, what value we place on human life, our morality, and our hopes for justice and life after death. People who don't see the pragmatism in theology aren't thinking about it enough.

Jesus thought that matters like the primacy of God and the afterlife are deeply pragmatic and highly important.

Monday, June 29, 2020

Arguing For Jesus' Self-Perception

Hawk recently started a thread that was partly about how to argue for and from Jesus' self-perception. Did he view himself as God? If so, what are the implications? How should we go about arguing for and from our answers to these questions? And so on.

One of the issues that came up was the validity of arguing for the historicity of Jesus' identity claims based on the general reliability of the documents that report the identity claims. And that is a valid approach and one that's sometimes neglected.

But we can, and sometimes should, appeal to more than the general reliability of the documents. We should be open to using every argument we have, though there's no need to use every argument on every occasion. It often makes sense to be selective, even highly selective (e.g., because of time constraints).

One question to ask, then, is what lines of evidence we have for Jesus' self-perception that meet multiple standards of evidence simultaneously. The more, the better. There's no need for the evidence we cite to meet multiple standards, but it is helpful.

I discussed an example in a post late last year. We have many, often significantly independent, lines of evidence that Jesus viewed himself as the messianic figure of Isaiah 9. And I've argued elsewhere (linked in the article cited above) that the figure in Isaiah 9 is God. The evidence for Jesus' identifying himself as that figure comes from all four gospels, both from Jesus' words and his deeds, in both subtle and explicit forms, with partial corroboration from early non-Christian sources, with partial corroboration from non-conservative modern New Testament scholarship, etc. I've written a lot about Isaiah 9 over the years, and I'll be discussing it further during the upcoming Christmas season. But even if we just take into account what I've already posted, I think there's a strong case that the figure of Isaiah 9 is God and that we have many, highly varied, and highly reliable lines of evidence that Jesus identified himself as that figure.

I encourage people to research the issues surrounding Jesus' self-perception, and develop arguments about the subject, in ways that take the multifaceted nature of the evidence into account. Don't just look at Jesus' words. Look at his deeds as well. Think about the Old Testament backdrop of his life and other relevant contexts. Look at the subtle assumptions and allusions in his other comments, not just his comments you're most focused on. Ask yourself if there are some ways in which the evidence is corroborated by ancient non-Christian sources or modern non-conservative scholars, for example. There will be different degrees of evidence for different conclusions, and you'll have different degrees of confidence accordingly. But it's important to gather a large amount of evidence, even if the levels of probability vary a lot.

Part of what's so significant about approaching the issues in this manner is that the cumulative effect adds to the credibility of the argument. If Jesus perceived himself in a certain way, especially if that self-identification was of a more central nature, there's a better chance accordingly that his identifying himself that way will be reflected in more places and more often. It doesn't follow that we can dismiss a claim about his self-image if there's only one line of evidence for it, it's only reflected in a couple of places, or something like that. For a variety of reasons, even the features of Jesus' alleged self-perception that are less evidenced can be credible (people aren't equally revealing of every aspect of their self-perception; our historical records are so partial; etc.). But there's especially good reason for accepting and arguing on the basis of portions of Jesus' self-perception that are evidenced in the sort of multifaceted manner I'm focused on here.

Thursday, May 14, 2020

Craig on eternal sonship

A sequel to this post:


Craig seems to think that in order to reject eternal generation, he must reject ontological sonship. If so, that's confused. These are theological metaphors. Metaphors are open-textured. Metaphors have multiple connotations. As such, most authors don't intend for every connotation of a metaphor to be in play. So the interpretive question is to identify the intended connotation.

Consider some of the connotations of fatherhood and sonship: fathers preexist sons, fathers age, fathers die, fathers and sons are embodied agents, sons undergo a maturation process, sons result from sex between a father and a mother.

When the NT uses father/son language for two persons of the Trinity, these connotations are clearly off the table. They reflect sheerly human things incompatible with deity. So the intended connotation(s) of the father/son terminology in NT Trinitarian usage is narrow. 

One connotation of the metaphor is derivation. Since that's incompatible with his position (I agree), he demotes the father/son terminology to the economic Trinity. It doesn't seem to occur to him that another connotation of the father/son metaphor is representation. A son resembles his father (like father/like son) and a son is especially qualified to act on behalf of his father, as his father's agent. Both are grounded in ontological sonship. 

Is God the Son Begotten in His Divine Nature?

Regarding this article:


1. I agree with Craig's critique of eternal generation.

2. I'm not going to comment on his general alternative (pp25-26). I don't care to get into the weeds of exegeting and assessing it. 

I've articulated my own model of the Trinity on numerous occasions. I'll stick with that.

3. However, a basic problem with Craig's position in this article is reducing the Father/Son distinction to the economic Trinity. That's mistaken because, on occasion, the NT clearly uses "Son of God" (or "Son" for short) as a divine title. His identity as the ontological Son of God figures in his deity. If he's the Son of God, then by implication he's divine. Reducing the Father/Son distinction to the economic Trinity can't explain that entailment in NT usage. And it's not a minor point. 

Tuesday, April 21, 2020

10 or so dumb reasons to reject the Trinity


Good thing it amounts to a nice round number. If they only had 9 reasons, I might still be hanging in the balance, but that tenth reason is the clincher tipping the scales for unitarianism!

In fact, their ten reasons seem to be more than ten in some respects, but repetitious in other respects, so my numbering will go over ten. 

1. God cannot die

An obtuse objection to the Incarnation. If Jesus just is God, then Jesus can't die. But of course, that's not the Trinitarian position. Rather, Jesus is a composite individual: the divine Son in union with a human soul and human body. So Jesus vis-a-vis his body can die. 

That's analogous to dualism; we say Methuselah died when he underwent biological death, even though he has an immortal soul.

The physical death of Jesus is a necessary but insufficient condition for atonement. 

2. Does God need to be resurrected?

This piggybacks on the same blunder as #1. If Jesus just is God, then he doesn't need to resurrected, but God Incarnate is subject to resurrection. 

3. Unless you're a hypostatic union–a composite of two natures–Trinitarian the resurrection offers no hope for you

That's hard to respond to because it's not an argument. It's unclear what the claim amounts to. It's not incumbent on Trinitarians to reconstruct the intended argument.

Is the claim that unless the redeemed are just like the redeemer, there's no hope for the redeemed? Is that the general principle? If so, how does that follow?

In the case of Jesus, what is resurrected isn't the hypostatic union but the body. The death of Christ didn't dissolve the hypostatic union. The soul remained in union with the Son.

What was lost was biological life. Why must the nature of Christ parallel human nature in every respect for the physical resurrection of Christ to parallel the physical resurrection of humans? 

Strictly speaking, a resurrection doesn't require an atonement but an exercise of divine omnipotence. At the general resurrection, the damned will be raised, but not because they were redeemed. 

4. Jesus can't be a mediator between God and man if he is God

The video keeps repeating the same blunder. If Jesus just is God, then he can't play mediator between God and man. But once again, that's a straw man. Why are the unitarians on this video unable to accurately represent the position they presume to debunk? 

5. A God-man can't be tempted and so can't overcome sin–because he was made in every way like this brothers

i) That does raise some theologically significant issues. I've discussed this objection on several occasions. For instance:



ii) To begin with, Heb 4:15 is hyperbolic. Taken without qualification, this means Jesus is tempted to have sex with teenage boys or handsome twenty-something males. Yet that's only be possible if Jesus is homosexual. And if he's homosexual, then he's impervious to heterosexual temptation. At best, a unitarian has to contend that Jesus is bisexual. 

iii) The unitarian alternative fails to explain what makes Jesus sinless. What makes him the exception to the universal rule that humans are sinful? Did God protect him from succumbing to sin? What gave Jesus a special advantage to resist sin? 

6. A God-man can't ask God to bypass the cup because he'd already knows the answer 

i) In a two-minds Christology, the human mind of Jesus is not omniscient.

ii) In addition, it's psychologically possible (indeed, commonplace) to know your duty but be emotionally conflicted about your duty and wish to avoid an especially onerous obligation. And keep in mind that this was a voluntary mission. A self-imposed duty. The Son had no absolute obligation to save sinners. 

7. A God-man can't authentically overcome to succeed where Adam failed. Only a human Jesus can set the example 

i) This assumes the primary role of Jesus is to set an example. Yet even on unitarian grounds, Jesus often does things most of us can't, like performing spectacular miracles.

ii) Salvation isn't a contest between evenly-matched contenders. It's not about fair-play. If a weak swimmer is drowning until a lifeguard saves him, that's because the lifeguard is a stronger swimmer. You might complain that the lifeguard has an unfair advantage, but that's why he can rescue weaker swimmers from drowning. It's not about emulating the lifeguard. His role is not to set an example. He role is to have superior swimming skills.

8. Different versions of the Trinity

True, and there are different models of unitarianism. A unitarian can be an Arian, Socinian, deist, Molinist, open theist, fatalist, predestinarian, Muslim, Rabbinic Jew, or goddess worshiper. 

9. Sola scriptura 

Sola scriptura incompatible with subordinating our theology to extrabiblical language and conclusions of later church councils? Trintarians are expected to agree with key metaphysical terms defined in the church councils of the fourth century, viz. the Tripersonality of God, how a divine essence can be shared between persons. 

i) It's true that sola scriptura is incompatible with rubber-stamping the formulations of ecumenical church councils. However, sola scriptura doesn't rule out the use of extrabiblical language. What matters is not the words we use but the concepts. Do extrabiblical words convey biblical concepts? 

ii) It's true that Protestants should scrutinize conciliar formulations and reject them if they run counter to the witness of Scripture. But many Bible scholars have made a detailed exegetical case for the deity of Christ and Incarnation of the Son (not to mention the Trinity in general). So this objection is at best directed at high-church Protestants. 

iii) Moreover, there are Trinitarians like Herman Alexander Röell, B. B. Warfield, Paul Helm, John Frame, John Feinberg who do takes issue with the Nicene paradigm. 

10. At odds with OT monotheism

i) Compared to creatures and false gods, there are three agents who stand out in the OT: Yahweh, the Spirit of Yahweh, and the Angel of Yahweh. These are presented as occupying the divine side of reality. 

ii) The representation of God as an old man on a throne is anthropomorphic. God has no actual appearance. 

iii) In the OT, Yahweh doesn't represent the person of the Father in the NT. OT usage isn't that discriminating. To the contrary, the NT repeatedly represents Jesus as Yahweh Incarnate. 

11. Trinitarians could start by explaining how two of us can share the same essence of humanity and be two beings but when three persons share the same essence of divinity, they're one being.

i) "Being" is a very generic concept. A Trinitarian could consistently say that God is one being and three beings. The word "being" doesn't do much conceptual work. It isn't a discriminating descriptor. It's more of a verbal placeholder. 

ii) Human beings exemplify a human nature, as properties instances. Each human being is an individual sample of human nature. A concrete, finite instance or copy. 

iii) By contrast, the divine nature is not some abstract generic essence that exists over and above or independent of the Trinitarian persons. The divine nature isn't separable from the Trinitarian persons. God is the exemplar. Each person exhaustively contains the entire essence, not a sample. The Trinitarian persons aren't copies of a divine nature 

12. Speculations about Jesus having two natures imagines that somehow in the one Jesus there is an eternal divine nature and also a complete human nature consisting of a body inside the one person possessing both natures is supposed to be the divine person, the second person of the Trinity.

i) This is hard to comment on because the sentence doesn't scan. As it stands, the sentence is somewhat unintelligible. 

ii) The complete human nature consists of a human soul (or mind) as well as a human body.

iii) "Person" is a term of art, and the meaning varies depending on whether we're working with Patristic usage, Cartesian usage, modern philosophy of mind (e.g. first-person viewpoint). 

iv) Some Trinitarians have reservations about an anhypostatic union. Details aside, the basic idea is that the body and soul of Jesus don't exist apart from the hypostatic union but by virtue of the hypostatic union. They have no independent existence. The combination only exists for purposes of the Incarnation.  

13. Such a divine person would be playacting anytime he didn't know something or couldn't do something or had to overcome temptation. 

Unless you're an open theist or Mormon, some of God's interactions with Adam, Abraham, and Moses are playacting, as if God is uninformed and indecisive. 

14. "God the Son" doesn't appear anywhere in the NT.

In the NT, Jesus is called" "God" and "the Son of God". So "God the Son" is a derivative biblical title that combines two things said about Jesus in the NT. 

15. Unitarians suffer from a prejudice about complexity. Yet there are things in the created order which run deeper than the human mind can fully fathom. It that's the case, then we'd expect God to be more complex than his finite creation. There's no presumption that God will be transparent to human reason. To the contrary, that's an antecedently false presumption. Unitarians worship a man-sized God. But if God exists, there will be truths about God we can't fully absorb due to our innate intellectual limitations. 

Thursday, February 20, 2020

Is Jesus the true God in 1 John 5:20?

R. Schnackenburg,82 who has given us the best commentary on 1 John, argues strongly from the logic of the context and the flow of the argument that "This is the true God" refers to Jesus Christ. The first sentence in 5:20 ends on the note that we Christians dwell in God the Father ("Him who is true") inasmuch as we dwell in His Son Jesus Christ. Why? Because Jesus is the true God and eternal life. Schnackenburg argues that the second sentence of 5:20 has meaning only if it refers to Jesus; it would be tautological if it referred to God the Father. His reasoning is persuasive, and thus there is a certain probability that 1 Jn 5:20 calls Jesus God—a usage not unusual in Johannine literature. Raymond E. Brown, 'Does the New Testament call Jesus God?', Theological Studies 26 (1965), 558.

Monday, February 10, 2020

Is the Angel of the Lord a Christophany?

1. Many Christian theologians contend that the Angel of the Lord isn't just a theophany but a Christophany in particular (or a theophanic Christophany, to be precise). And that may be the case. However, Trinitarian hermeneutics and Christian messianism don't require that. Moreover, it can be counterproductive when Christian theologians are too insistent on that identification

2. It's not as if Yahweh is the Father and the Angel of the Yahweh the Son. I don't assume that when Yahweh sends the Angel of the Yahweh (or the Angel comes from heaven), that's the Father sending the Son. 

3. Strictly speaking, Yahweh is the Trinity. When I talk about three divine persons in the OT, it's necessary to have separate designations for each to refer to them, and so I use the name Yahweh to distinguish one person from the other two (Yahweh, the Angel of Yahweh, and the Spirit of Yahweh), but that's semantic rather than ontological. It doesn't mean, at a metaphysical level, that one of them is Yahweh while the other two are not. Likewise, the "Spirit of God/Yahweh" doesn't stand in contrast to the nature of Yahweh, as if Yahweh is physical. There's a difference between the ontology of the persons and the semantics of naming. Although the names represent distinct persons, Yahweh is not a particular designation for the Father. 

4. In the case of the Spirit, that designation corresponds to one particular person of the Trinity because the usage is consistent across both Testaments. Likewise, in NT usage, "the Father" and "the Son" are uniform designations for particular persons of the Trinity.

But "Yahweh" is more flexible. Indeed, in NT usage that's typically a title for Jesus, via its LXX equivalent (Kurios). 

5. Many Christian theologians think there's a direct parallel between Yahweh sending the Angel and the Father sending the Son. But not only is that comparison anachronistic, but it's apt to backfire. If you assume that the Father is the default referent of Yahweh/Elohim, then evidence for the OT divine messianism is limited to a handful of prooftexts. 

6. Keep in mind that disproving unitarianism doesn't necessitate correlating the Angel of the Lord with a particular person of the Trinity. To disprove OT unitarianism, it will suffice to show that there's more than one divine person–and not which is which or how the persons and designations matchup. 

7. In addition, it would be extremely misleading for a unitarian God to reveal or manifest himself–in word or deed–as if there's two or three of him while he inveighs against polytheism and idolatry. A unitarian God would be working at cross-purposes with his true nature and corrective agenda if he did that.

8. In many situations it is prudent not to argue for more than you need to to prove your point. If a less ambitious argument will get the job done, that's often better because it has a lower burden of proof.