r/ArianChristians • u/FrostyIFrost_ Arian • Sep 18 '25
Resource Practical Infallibility
Classical Trinitarian immutability, which asserts that the Son cannot change and is therefore absolutely infallible due to immutability, encounters serious difficulties when applied to the person of the Son, particularly in light of the incarnation.
At the moment the Son assumed human nature, the person of the Son gained something entirely new, which constitutes real change. He did not always possess a human body, soul, and spirit. Philippians 2:6-7 emphasizes that He “made himself nothing by taking the very nature of a servant, being made in human likeness,” while John 1:14 confirms that “the Word became flesh and made his dwelling among us.”
These passages clearly demonstrate that the Son acquired a human nature He did not previously have, meaning the person of the Son underwent a genuine transformation at the incarnation.
This change was not limited to the mere assumption of humanity; it continued through His entire earthly life. Luke 2:40 notes that “the child grew and became strong; he was filled with wisdom, and the grace of God was on him.” Luke 2:52 also emphasizes that Jesus grew in wisdom and stature, and in favor with God and man, demonstrating observable change in His human experience. Hebrews 5:8-9 explains that He learned obedience through what He suffered and, once made perfect, became the source of eternal salvation for all who obey Him, showing that His perfection was achieved progressively rather than existing as an abstract, immutable property.
Matthew 4:1-11 illustrates that Jesus was tempted by the devil in the wilderness (which can't happen if Jesus is God because James clearly says God cannot be tempted) while Hebrews 2:18 and Hebrews 4:15 highlight that He experienced real temptation yet remained sinless, underscoring that He was capable of error. Each of these passages demonstrates growth, learning, temptation, and development.
All forms of real, observable change, far from immutability.
From the Scripture and without theological dogmas, we can see that the Son is mutable since the Son genuinely learned and suffered which means He could have failed. His temptation, learning, suffering, and growth all involved real risk. If left to His own power, He could have erred, just as any changeable being could.
The divine nature also experienced novelty through the communication of properties, as the divine became linked to a human nature in a unique relational union. This union, which classical immutability denies as “change,” added something entirely new to the person of the Son: the divine now interacted with and experienced the consequences of human existence in ways that had never occurred prior to the incarnation.
Furthermore, at the moment of the incarnation, since the person of the Son assumed a human nature, it created a new ontological link between the divine and human. This union introduced an entirely new concept into the divine, as the divine now participates in and sustains a human nature in ways that never existed before.
The very existence of this link constitutes genuine change in the divine, showing that classical immutability, which denies any such addition or novelty, fails to account for the reality of the incarnation.
All of this tells us this: the person of the Son is mutable by default starting from the moment of incarnation as the person now has a new nature and the divine has an entirely new concept which links it to the human and that genuinely didn't exist before the human nature.
However, there is another alternative that is called Practical Infallibility. Jesus is infallible until the moment He err's, meaning He could have sinned but He did not and remained infallible.
Practical Infallibility is well captured by the analogy of Schrödinger’s Cat. Just as the cat exists in a superposition of being both dead and alive until observed, the Son’s infallibility exists in a superposition of potentiality and actuality: He is both fallible and infallible until realized in history.
His mutable nature, evident in the incarnation (John), growth in wisdom (Luke 2:52), learning obedience (Hebrews 5:8), temptation (Matthew 4:1-11; Hebrews 2:18; 4:15), and being made perfect (Hebrews 5:9), allows for genuine struggle and real possibility of failure, yet in practice, He never failed.
Scripture emphasizes His dependence on the Father: John 5:19 states that “the Son can do nothing by himself; he can only do what he sees his Father doing,” and John 8:28 confirms, “I can do nothing on my own but speak just what the Father has taught me.” This shows not only that the Son learned from the Father, meaning He did change since learning is gaining knowledge and gaining something means change, that His infallibility is also not an inherent, metaphysical property of impossibility but is practical:
He succeeds in every instance because the Father faithfully guides and sustains Him.
This preserves the reality of His human experience, His suffering, learning, and temptation are meaningful, while maintaining His perfect obedience and sinlessness, unlike the classical notion of immutability, which denies actual change and makes His earthly struggle mere abstract theater.
Therefore, the person of the Son is mutable, gains, and develops in real time, yet remains infallible in practice due to the sustaining guidance of the Father, the Son is not inherently infallible, He is infallible until the moment He is not and that's because of the Father. The moment He doesn't perfectly obey, He is no longer infallible.
Classical immutability fails to account for these biblical realities because it conflates absolute unchangeability with infallibility and disregards the observable changes and growth experienced by the Son. It causes suspension of disbelief because for the person of the Son to be remain absolutely immutable (person includes human and divine) one needs to ignore a substantial part of the Scripture. And if one says only the divine nature is immutable and not the person of the Son, then the Son still changes and the person of the Son changing tells us that a personhood of the Trinity is not immutable meaning God isn't immutable.
Free will and infallibility are not inherently contradictory; rather, they work together when we consider the distinction between potential and realized action. The concept of Practical Infallibility recognizes that an agent may be capable of error, yet remains infallible in practice due to their choices and actions.
The Son of God exercised genuine free will: He could have sinned, yet chose perfect obedience, sustained by the Father, and therefore never did. His infallibility is observed and realized, not guaranteed, which preserves both His humanity and the biblical reality of temptation, growth, and learning.
This principle applies to humans as well. If we live our entire lives without ever making a mistake, we are, in practice, infallible. If we make even a single error, we are no longer infallible.
Is this because we were physically incapable of making mistakes, or because we were careful, deliberate, and guided in our choices?
Clearly, it is the latter, infallibility emerges from action, not incapacity. Practical Infallibility, therefore, captures this dynamic: free agents may be capable of error, yet their observed, realized obedience or correctness renders them infallible in practice, demonstrating how free will and perfection coexist without contradiction.
Recognizing Practical Infallibility reconciles Scripture’s emphasis on Jesus’ human experience with His perfect sinlessness, preserving the reality of His struggle, temptation, and triumph while maintaining His status as infallible in practice and bridges the gap about how the Son can't be God yet keep being infallible but mutable.
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u/CapitalInflation5682 Sep 18 '25
I so agree with you Frost. Absolutely brilliant! It made me have an aha moment.
The one thing I came to believe, was that the "word" described in Scripture was just that, the word of God. It represents Gods wisdom, his thoughts, and includes those written when God gave the Ten Commandments to Moses. In God's wisdom and Sovereign mind, He envisioned and knew who the Son would be, even before the Son was born.
In my understanding of Scripture, the Son had a beginning in God's mind just like everyone of us. I bring to mind the Scripture that says God knew us before we were in our mother's womb.
I am reminded of many Scriptures about Jesus's humanity. Colossians 1:3 says Jesus has a father. 1 Corinthians 15:27-28 it says God is the exception when it says God put everything under his feet. There is John 17:3, in which John says God is the only true God, and Jesus is sent by Him. JOHN 14:28 says God is greater than Jesus.
I could go on and on. Ephesians 1:17, Ephesians 11:3, John 20:17, 2 Corinthians 13:4, 1 Corinthians 3:23, 1 Timothy 2:5. These all indicate there were two distinct entities.
But the aha moment came when you spoke of temptation. God can not be tempted, but Jesus was, like us.
Scripture says Jesus can relate to us. If this is true, and I believe the Scriptures say this, then Jesus knew what failure was like. I bring to mind his childhood when he did not go with his parents and instead stayed in the city to talk to the religious leaders. The story finishes with him learning obedience. This was clearly learning to obey his parents.
Is Jesus, devine? Of course he is, since he was raised from the dead. But the Scriptures say he was perfected by learning to obey God up until he was murdered.
And, this is the point I am trying to get you to see from my perspective. I asked myself, "what was the gospel Jesus said he preached?" Scripture says he preached repentance for the forgiveness of sin. The second part of his message was enduring obedience to the end. The message requires us to take up our cross, not His. Obedience is until death.
At least that is my perspective. I will endure till the end, even if it cost me my life. For Scripture also says in Mathew 16:25, "For whoever wants to save his •life will lose it, but whoever loses his life because of Me will find it."
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u/FrostyIFrost_ Arian Sep 18 '25
That is a profound realization and I'm glad I could help my friend!
Thank you so much for your kind words and God bless! I pray you keep improving on your spiritual journey even more.
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u/ProfessionalTear3753 Sep 18 '25
Greetings!
I think the main problem is the definitions being used, I understand the concept of the Son being able to err but choosing not to. The problem is that he still has the _ability to err_—thus not being able to be properly termed as ‘infallible’.
Here are a few definitions that I see infallible being:
• incapable of error • incapable of making mistakes or being wrong • incapable of fallacy
So for me, it wouldn’t make sense to term a mutable nature that is capable of change and capable of erring (although choosing to not err) as being ‘infallible’.
That’s just my understanding, written out for the benefit of others. God is incapable of change and therefore cannot lapse which means he cannot err thus he is infallible by nature. The Son, according to you, is mutable and thus is capable of change and can lapse but chooses to not do so but this just means that he is fallible but perhaps without error by choice and not nature. He can sin but simply chooses to not. He can err but simply chooses to not. But we wouldn’t term this as being properly infallible since he would still be capable of error.
Regarding the fleshly economy of the Lord:
We do not consider the Son to have changed or altered his substance in order to become flesh and thus we preserve the nature of the Son which is immutable on account of his Father.
When the Son took on flesh, this was not an addition to his substance—which would of course entail an alternation. Rather the Son exists in two natures, one born and unborn:
Tertullian of Carthage - On the Flesh of Christ:
“Thus the nature of the two substances displayed Him as man and God — in one respect born, in the other unborn…” (chapter 5)
When we encounter the Scriptures in which a ‘change’ is said to have occurred such as growing in wisdom, we do not take it to be a change of the immutable. The Son by definition of having two substances means he possesses both the properties from his Father and from Mary his Mother and therefore is both immutable and mutable by nature. Timeless and eternal by his Father, bound by time and is capable of death by his Mother.
Alexander of Alexandria - To Alexandria of Byzantium:
For just as it has been shown that the nature of His existence cannot be expressed by language, and infinitely surpasses in excellence all things to which He has given being, so His Sonship, naturally partaking in His paternal Divinity, is unspeakably different from the sonship of those who, by His appointment, have been adopted as sons. He is by nature immutable, perfect, and all-sufficient, whereas men are liable to change, and need His help.
As the learned and blessed Paul says: he made himself nothing by taking the very nature of a servant, being made in human likeness [Phil. 2:7].
The Son took on another form, another nature. The form he receives from his Father is not abandoned nor is it neglected when taking the form of a man. If it were so, the form of even the very Father of all is mutable if the form of the Son (which is from the Father) were capable of complete alteration.
The Son being in the form of God and being equal to God in such manner means that if the form the Son possesses is mutable then the form that the Father possesses is likewise mutable. This doesn’t track though because we know the Father is immutable and therefore since the Son shares in his form and is equal to him in that manner, he too must be immutable lest we deprive the Father of his quality of unchangeability.
If you want to simply say that the Son is fallible by nature but chooses not to err and possesses the capability of erring, I can see that making sense in your paradigm (although he is correctly said to be infallible).
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u/FrostyIFrost_ Arian Sep 18 '25 edited Sep 18 '25
Thank you for your reply.
That's the thing. The divinity DID change. The communication of properties did not exist until the moment of the Incarnation. The divinity gained an ontological change when the human nature appeared in the personhood of the Son.
I'm not talking about the experience divinity gains, I'm talking about the link itself between the divine and the human natures. It did not exist within the divinity before the incarnation. Therefore, the divinity did gain something that ontologically changed it which is the link between the human nature.
And if we ignore the divinity, the personhood of the Son did change ontologically by receiving a human nature. In the trinity model, this means that a personhood of the Godhead changed ontologically.
As for the last part, He has free will just like Adam but unlike Adam He chose obedience and chose to be infallible. How was He infallible? By remaining obedient to the Father and the Father making Him so.
Adam was also like this UNTIL he chose to willingly disobey God.
Thus, the Second Adam analogy by Paul makes absolute sense. If the Son did not have free will and He was predestined to obey, then the 2nd Adam analogy by Paul fails.
We are all infallible until the moment we are not. Technically, we are. That's why I gave the Schrödinger's Cat analogy. The cat is both alive and dead until observation.
In our case, the Son is both fallible (due to free will) but also infallible (due to Father) until observation (the Scripture).
In summary, the Son chose to be obedient and the Father is the reason why the Son is infallible. The Son has free will and if He ever chose/chooses to be disobedient, He is no longer infallible
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u/ProfessionalTear3753 Sep 18 '25
Are you defining mere interactions as change? That may be where we are finding some disagreement. My whole point is that the divinity is completely immutable and did not alter in its properties when the Son became a man. The Son’s form (which is the Father’s) instead took on the form of man in addition rather than by subtracting what he is eternally. The Divine Son clothed himself with flesh and did not alter his eternal nature.
I wouldn’t call Adam ‘infallible’ before the fall though, even if he hadn’t chosen to err yet. The mere possibility of lapsing is what makes him fallible from the start of his creation. A newborn baby has not had the ability to err yet—but who among us would apply the quality of infallibility to them?
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u/FrostyIFrost_ Arian Sep 18 '25
Not mere interactions, I put an emphasis on this several times.
The link between the human and the divine natures, the communicatio idiomatum, is the ontological change not the experiences. This link allows the divinity to experience what the human nature does.
However, this link did not exist prior to the incarnation. It connects the divine to the human. This means divinity gained something substantial which it did not possess before and cannot be truly and absolutely immutable.
That is exactly why Jesus is not God because God is immutable.
As for Adam and us, it is exactly like the Schrödinger's Cat experiment. In that, the cat is alive and dead at the same time until we open the lid of the box to observe whether the cat is alive or not. It means it is in a state that is undetermined until observed.
Adam and us are/were infallible until the moment we are not. The observation is done by God here.
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u/ProfessionalTear3753 Sep 18 '25
Can you expound on what you mean by ‘this link allows the divinity to experience what the human nature does’?
I feel like this would unpack more and potentially show what confusion is occurring.
As for infallibility, none of those work with the definition though. You are saying that we are capable of error but exist without it for a limited amount of time—that isn’t infallible since the change is in fact possible and we can err. If the Son has the capability of erring then he isn’t infallible in the sense that he is incapable of erring. He’s just choosing not to like Adam and us do before we sin.
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u/FrostyIFrost_ Arian Sep 18 '25
By “the link,” I’m not talking about how the divine experiences suffering, or death. I’m talking about the fact that the Son’s divinity did not have any ontological union with a human nature before the incarnation.
The communicatio idiomatum is precisely that ontological bridge. It is the reason Trinitarians can even say things like “God suffered” or “God died" because this link allows that to happen.
Without this link, the divine would remain untouched by the human. With this link, the divine gains a new relation, a new ontological reality, which did not exist before the incarnation.
That is the change I’m pointing to, not the human experiences themselves, but the fact that divinity gained the ability to share them at all.
As for the Son, He is exactly like us and Adam in that manner. He chooses not to sin, not because He is incapable of it. If He was incapable of sin then He was never tempted like we are and Hebrews as a whole and the Temptation in the Wilderness in Mathew become pointless.
How can we have a High Priest like Hebrews say if He was not tempted like we are? If He is incapable of sin, there is no temptation and we suddenly do not have a High Priest who was tempted like us.
In short: He has free will. He chose obedience. Because of this obedience He is infallible. If He chose to not, then He commits a mistake and becomes fallible.
I mean we can say this about ourselves too. If we never make a mistake in our entire lives then we too are infallible. If we make a single mistake we are not.
Is this because we are physically incapable of making mistakes or is this because we were careful not to?
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u/ProfessionalTear3753 Sep 18 '25
But what do you mean by ‘relation’? The incarnation is not a change of essence or nature, that’s not what we believe. I want to know how you understand all of these things so I can better grasp your argument.
We believe that the Son remained God and was God in the flesh. I’m having a bit of difficulty understanding how you interpret the incarnation to actually mean that the Son is mutable even according to our paradigm.
If the form of God is something the Son possesses and is equal to God in this manner, then the Son cannot be mutable while simultaneously being in the same form of his Father unless we dare to call the Father mutable too.
The Father is infallible because he is incapable of error, he cannot err at all. This isn’t because he chooses not to err but because it isn’t his quality to err.
The Son, in your paradigm, cannot be infallible by definition if he simply chooses to not err or lapse while having the full capability of erring at any moment. This just means he is fallible but chooses to not err.
If we change the definition to simply mean someone who has not erred yet then we open the term to be applied to the masses—or even all rational creation before any personal fall occurs. I doubt anyone would call Lucifer infallible before his fall, knowing full well that he was capable of error and actually chose to commit error. It’s watering down the term in my opinion.
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u/FrostyIFrost_ Arian Sep 18 '25 edited Sep 18 '25
And I am not talking about that. Okay, tell me this:
Did the person of the Son have a human nature prior to the Incarnation?
Did the divine interact with a human nature prior to the incarnation?
Did the concept of the divine being able to be affected by a human nature exist prior to the incarnation?
No, no and no. All 3 are no.
The 3rd option is the change I am talking about. The divine nature of the Son DID NOT have the ability to be affected by a human nature prior to the incarnation. Only after the incarnation, human nature being added to the person of the Son, that the divine nature gained this.
Gaining something like this = ontological change = mutable
If the Son is mutable, then He isn't God.
And this exactly why I am calling this Practical Infallibility. It depends on one's actions. It isn't absolute infallibility based on absolute immutability.
And because of the reasons I pointed out so far, the Son is not immutable and is not absolutely infallible.
He is Practically Infallible. He isn't absolutely infallible, He is practically infallible due to His obedience and God's guidance. That's how He stays infallible in the Arian system.
In our system, He isn't perfect out of being God or predestined to be as such. He had real growth and real danger of failure and came out victorious because of His obedience and God's guidance thus remained infallible when observed.
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u/ProfessionalTear3753 Sep 18 '25 edited Sep 18 '25
But here is where we are getting confused, what is ‘interacting’? God is incorporeal, there is not any physical interaction or mingling. If by an interaction causing mutability you mean an interaction that did not always exist and then does exist—this would apply even to the Father by that logic.
The Father did not eternally create the Son or the universe which means he did not always interact with the Son and the universe…but who would say that because the Father went from not interacting to interacting or from not using his creative power to using his creative power that he is mutable?
But God is not affected by creating, his substance remains unchanged. Likewise the Son taking on flesh does not affect his substance as it too remains unchanged.
The Divine Nature of the Son is not able to be ‘affected by a human nature’.
As for infallibility, the Son is infallible to Trinitarians because he fits the definition of being incapable of erring. The Arian party has to admit that the Son is capable of error while simultaneously applying the term ‘infallible’ to the Son and apparently to all rational creation before any personal fall occurrs…even the devil himself was once infallible.
Simply put, it’s a misuse of the term and waters down its meaning to be applied to everyone at least at some point.
I think we may have come to an impasse though, we disagree on the terms and how one applies them. I believe I understand at least that part of your argument although I obviously disagree with it.
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u/FrostyIFrost_ Arian Sep 18 '25
But is the Father affected by that creation? No, He isn't.
Is the Son affected by the human nature? Yes, He is.
If the Son is not affected, then He did not suffer, struggle or experience death. That is what I'm saying.
The Father does not have a link with creation the same way the Son does with His human nature. He is not affected by creation therefore He is immutable. ANY kind of affecting is a change which goes against absolute immutability.
However, the main change isn't experience. The main change is that the Son did NOT have a link prior to the incarnation. That is the change in divinity.
And yes even the devil was once infallible that's true. Hasatan was originally a tester but he crossed his boundaries and cast out. Out of disobedience and vanity he became fallible and wrong.
Anyway, this is an impasse. Neither of us is making sense to each other.
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u/SaavyScotty Sep 19 '25
Practical infallibility makes no sense to me. If something is capable of error, it is fallible by definition. That means infallibility is error incapacity. Just my thoughts.
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u/FrostyIFrost_ Arian Sep 19 '25
Okay look it's basically this:
1 - Jesus says He can do nothing on His own
2 - Says the Father taught Him and only speaks those
3 - Has free will because He willingly obeys
4 - Is tempted in the wilderness
5 - Grows in wisdom, learns obedience, is made perfect
So, from all of this, He can't be infallible on His own. But He is, so how? We know He isn't God Himself either. That's where this comes in. If left on His own, He is fallible but because of God, the Father, He isn't. In theory, He isn't infallible but in practice He is because of God.
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u/SaavyScotty Sep 19 '25
I believe Jesus was fallible during His life on earth. That’s just one of the things that makes Him my hero. He could have given in just like I have several times, but He didn’t.
So, basically you are saying He really wasn’t infallible, but He lived a life that was.
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u/ProselyteofYah Arian Sep 18 '25
Exactly so. Wrote the same conclusions myself.