Mindwarden recently argued that Calvinism is internally incoherent when it comes to human nature, sin, and the incarnation. His claim is that Reformed theology “can’t have it both ways”—that if sin is accidental, humanity remains ontologically unchanged, but if sin is essential, Christ could not share our nature without sharing our depravity. He concludes that Calvinism destroys its own anthropology in trying to save Christ’s sinlessness.

Here’s his statement in full:

“If Calvinists say sin is accidental (not essential), then humanity’s essence/nature wasn’t changed by sin. Therefore, we remain ontologically identical to pre-fall Adam. There’s no ‘sin-nature.’

That means their own premise undermines the need for an immaculate conception or ‘special’ humanity for Christ. If sin doesn’t alter essence, then incarnation itself doesn’t risk corruption.
But Calvinists insist it does, hence their doctrine of ‘sin nature’ (which actually is not accidental in their soteriology but hereditary and total). They’re nothing but consistent in their inconsistency.

Either sin is accidental (then we’re unchanged), or sin corrupted our nature (then man’s nature was fundamentally altered, and they must explain how Christ escapes total depravity).
They can’t escape that dilemma. The ‘accidental’ claim saves Christ only by killing their soteriology.”

Mindwarden’s argument trades on a fundamental equivocation: the term nature can mean either
(1) essence—the essential properties that make one human, or
(2) condition—the moral and psychological state of that humanity.

When Reformed theologians describe sin as accidental, they mean that sin inheres in human nature, not as human nature. The fall did not make Adam cease to be human. He retained the same faculties (mind, will, emotion, and body) but each was now misdirected, turned away from God. The doctrine of moral corruption refers to the character of fallen humanity, not to the definition of humanity. Sinfulness describes what humans have become, not what they are by essence.

I don’t usually talk in metaphysical terms like “inhere,” but it’s important to be clear about what people mean when they use it. To say something inheres in another just means it exists in something else as a quality, not as that thing itself. Color inheres in a surface (the car may be blue or red, but it is still a car). It doesn’t exist floating around on its own. In the same way, sin inheres in human beings: it’s a feature of their moral character, not the substance of their humanity. Sin depends on human nature to exist; it feeds on it like a parasite. It can corrupt and twist what’s there, but it can’t exist apart from it or redefine what it means to be human.

So yes, humanity is “ontologically identical” to pre-fall Adam in essence or to glorified humanity in the eschaton but not in condition. Adam’s being remained, yet his orientation changed. His character became disposed to wrongness because of sin.

This distinction matters. A blind man is still a man. Blindness is accidental to humanity, yet it fully affects sight. Likewise, sin is accidental but pervasive in that it reaches every human faculty without redefining what it means to be human. But to speak of “pervasion” is metaphorical; in plain language, several concrete truths follow:

• Fallen humans cannot earn divine favor through moral effort.
• They are sinners through Adam’s representation and guilt.
• They are unable to believe apart from divine grace.
• They know God through creation and conscience but are disposed to unbelief because their characters are corrupted.

These are moral and covenantal realities but notice that none of these claims entail that you require two different ontological categories for humanness.

If we translate Mindwarden’s claims into basic metaphysical grammar, the problem becomes obvious.

Ask simple questions:

• Do humans have human properties?
  Yes (rationality, embodiment, moral agency, and dependence on God.)
• Is being sinful one of those essential properties?
  No. Sin isn’t part of what it means to be human. It’s a condition that affects human beings because of the fall, not a defining feature of what humanity is. For those like myself, sin is parasitic on human nature. It lives off what is good but adds nothing essential to it. The phrase sin nature is just shorthand for describing the moral character of people apart from grace, not some built-in ingredient of being human.

When Calvin writes that our “nature is not only destitute of all good, but so prolific in evil that it cannot remain inactive” (Institutes II.1.8), he isn’t redefining humanity’s essence. He’s describing the moral condition of the fallen man in relation to God: every faculty, power, and inclination is turned against Him. The corruption is total in extent, not essential to being a human being.

Calvin’s not claiming that human nature itself changed into something else after the fall. The passage is describing the corruption of human character and moral orientation, not an ontological transformation.

When Calvin says our nature is “utterly devoid of goodness” and “prolific in every evil,” he’s emphasizing the depth and extent of moral ruin, not redefining what it means to be human.:

8. But lest the thing itself of which we speak be unknown or doubtful, it will be proper to define original sin. (Calvin, in Conc. Trident., 1, Dec. Sess. 5). I have no intention, however, to discuss all the definitions which different writers have adopted, but only to adduce the one which seems to me most accordant with truth. Original sin, then, may be defined as a hereditary corruption and depravity of our nature, extending to all the parts of the soul, which first makes us obnoxious to the wrath of God, and then produces in us works which in Scripture are termed works of the flesh.
This corruption is repeatedly designated by Paul by the term sin (Gal. 5:19); while the works which proceed from it—such as adultery, fornication, theft, hatred, murder, revellings—he calls fruits of sin.
… [rest of quote truncated for brevity]
“Our nature is not only utterly devoid of goodness, but so prolific in all kinds of evil that it can never be idle.”

The Greatest Refutation: Common Sense and the Bible

Here’s Mindwarden’s line:

“If Adam is ontologically not different from us, Christ wasn’t either.
That logic erases Paul’s entire Second Adam typology. Romans 5 and 1 Corinthians 15 explicitly contrast Adam and Christ, not as identical humans. They’re two heads of humanity. Two orders of life: Adam brings death and Christ brings life. The first is ‘living soul,’ the second ‘life-giving spirit.’ The first is ‘of the earth,’ the second ‘of heaven.’ That’s not ontological sameness.”

This might sound sophisticated at first glance, but it collapses the moment you use your brain or read the text he’s quoting.

Paul isn’t contrasting species. He’s contrasting representative men. The entire typology in Romans 5 and 1 Corinthians 15 depends on Christ being the same kind of being as Adam. Both are men, both bear human nature, and both stand as covenantal heads of their respective orders—one of sin and death, the other of righteousness and life.

Mindwarden’s argument essentially boils down to:

“If Christ is human like Adam, then the contrast doesn’t work.”

But that’s the opposite of Paul’s point. The contrast only works precisely because Christ is human like Adam. He can reverse Adam’s curse because He shares Adam’s race. As Paul says, “since by a man came death, by a man came also the resurrection of the dead” (1 Cor 15:21). Christ redeems what He assumes. He saves men by becoming man.

If Christ were not ontologically identical to Adam—if He were some higher order of being unrelated to Adam’s kind—then there would be no federal correspondence at all. His obedience couldn’t stand in the place of ours, and His resurrection couldn’t guarantee ours. To deny their shared humanity is to destroy the logic of the Second Adam typology.

And really, the irony here is staggering. Mindwarden admits that Adam and Christ are both human beings— “two heads of humanity,” as he puts it but then turns around and says that means they’re not “ontologically the same.” How does that even make sense? You can’t be the head of humanity without sharing the nature of the body you represent. It’s literally in the name: Adam means man!

So the greatest refutation of this argument is simply common sense and the Bible. Christ and Adam are both men. That’s the whole basis of Paul’s analogy. The difference is not one of essence/nature/being/essential properties/ [whatever other categories for distinguishing a class of things] but of representation and obedience (two Adams, two men, two covenantal heads).

Christ isn’t a different species of being; He’s the true man, the restored image-bearer, the one who fulfills what the first man failed to do.

The traditional Reformed view (following Augustine) says sin is a privation—a loss of the original righteousness humans were created with. Even if you grant that definition for the sake of argument, it already defeats Mindwarden’s point: a lack or absence can’t be part of what something is by nature. You can’t define a thing by what it’s missing.

Even if we set aside the privation language, sin can be described as a positive disorder—a real twisting of the will and desire that emerges from human life after the fall. It’s not something added as a new part of human essence, but something that arises from humanity’s misuse of its own faculties. In that sense, sin is almost like an emergent property of fallen existence—dependent on human nature, expressed through it, but not identical with it. It tells us what fallen humans are like, not what humanity is.

So whether you think of sin as a loss (privation) or as a distortion (disorder), the conclusion is the same: sin is not necessary to human nature. It affects everything about human life, but it doesn’t redefine what it means to be human.

MindWarden has responded; I’ll engage the main points in order.

“If sin is truly accidental, then at least one naturally generated human must be able to exist without it.”

Response — Non Sequitur.

This conflates “accidental to essence” with “possibly absent within the same post-fall order.” Accidental means sin isn’t part of what a human is; it does not require a counter-instance inside the very regime where God has attached corruption to ordinary birth “in Adam.” Depravity can be accidental to human nature and yet inevitable given God’s post-fall arrangement. And Scripture already supplies sinless humans in other states/modes (Adam pre-fall, the glorified, and Christ), which is sufficient to show sin isn’t essential to humanity.

Think legal status, not biology: under a jus sanguinis policy, every child of citizen-parents inherits citizenship. That universality under a standing order doesn’t make “citizen” an essential property of being human. Likewise here: universality now doesn’t convert a non-essential feature into an essential one.

“You still insist Christ had to be conceived by the Holy Spirit to avoid inheriting corruption… If sin were merely accidental, there’d be nothing inherent in ordinary humanity to avoid.”

What’s at issue isn’t “humanity” as such but Adamic representation. By God’s ordering, Adam is a public person; those he represents come under his verdict and its moral effects. I’m not resting the point on Christ’s biological mode of entry. The claim is simpler: Christ was never represented by Adam. Representation is a juridical appointment, not a bloodline mechanic. Ordinary generation is the usual way God places persons under Adam’s headship, but the ground is Adam’s office. Christ, the last Adam (Rom 5; 1 Cor 15), stands outside the first Adam’s liability while sharing our humanity “in every respect—yet without sin” (Heb 4:15). That’s why corruption is universal for those in Adam without making sin an ingredient of human nature, and why Christ is sinless without ceasing to be fully human. In Paul’s terms, there are two covenant heads—in Adam or in Christ.

“By claiming that ordinary generation necessarily transmits depravity, you’ve admitted that corruption is a natural property of humanity after the fall… the human essence has been altered in its actual instantiation.”

“Natural” in this context means native to us as born into this judged order, not essential to the species. An oak infected with rot is still oak.

“Either sin is accidental and the virgin birth is unnecessary, or sin is essential and Christ cannot share our nature.”

False dilemma.

Sin is non-essential to humanity (proved by sinless humans in other states/modes: Adam pre-fall, the glorified, and Christ), yet inevitable in this era for those born under Adam. I’m not grounding Christ’s sinlessness in His biological mode of entry; my claim is simpler: Christ was never represented by Adam. By divine appointment, Adam’s verdict attaches to those he represents (ordinarily by birth “in Adam”); Christ stands outside that representation while sharing our humanity “in every respect—yet without sin.”

As for the virgin birth: it need not function as the reason Jesus lacked original or actual sin. It can stand within God’s redemptive ordering—as a sign of divine initiative, fulfillment, and new creation (in step with Scripture’s pattern of miraculous births)—without serving as the metaphysical ground of Christ’s holiness. On my view, representation explains universality now without making sin part of human essence, and non-representation explains Christ’s sinlessness without denying His full humanity.

And note: you affirm the virgin birth while denying original sin. That concedes the doctrine has independent, biblical-theological reasons (divine initiative, new-creation, promise-fulfillment, Davidic/Isaianic pattern), not a supposed role as a “mechanism” to dodge an essence-level defect. Even on your premises, the virgin birth stands without making sin essential to humanity; on mine, we simply agree on those order-reasons while grounding Christ’s sinlessness in His not being represented by Adam.

“Every time you redefine ‘accident’ or ‘nature,’ you’re just changing labels… THAT’S equivocation.”

No—there’s no label swap here. I’m the one who removed the ambiguity by defining terms so we don’t talk past each other. You’re requiring an equivocation on nature to make your dilemma bite. “Human nature” names the essential properties of being human; “sin nature” (as I’m using it) refers to a moral condition of humans in Adam after the fall. Those are different categories.

A quick, plain example: some men have brown hair. That’s a real fact about those men, but it isn’t a fact about all men—and it certainly isn’t a fact that defines what it is to be a man. Likewise, there are facts about humans post-fall that are not definitional of humanity as such. Clearing up that ambiguity in nature / sin nature is what collapses your argument.

Here are the two modalities I’ve been explicit about:

Essential = belongs to every human in any state and by any mode (pre-fall, post-fall, glorified; created, ordinarily generated, or uniquely sent). Inevitable in this order = belongs to those ordinarily generated under Adam in the post-fall economy, by God’s appointment.

Your critique conflates these. That’s the equivocation. Once the modalities are kept distinct, my three claims line up cleanly:

All ordinarily generated humans are corrupt (inevitable in this order). Christ stands outside Adam’s representation and so is not corrupt (different representative relation, not a different essence). Therefore sin is not essential to human nature (since Scripture gives humans without sin in other states/modes: Adam pre-fall, the glorified, and Christ).

“Appealing to Augustine’s privation doesn’t help. A privation that is universal, hereditary, and incurable apart from re-creation becomes a defining structural defect.”

Those adjectives—universal, hereditary, incurable apart from grace—describe reach and remedy, not essence. A lack that is everywhere present in a given order of history does not therefore become constitutive of what a human is. On the Augustinian/Reformed account, privation means the loss of original righteousness; an absence cannot be an essential constituent of a nature without collapsing the pre-fall Adam and the glorified saints into “non-human,” which is absurd. So even on terms you disagree with, privation does not make sin essential.

And set privation aside: speak instead of a positive disorder of will and affections in the fallen order. That still tells you what fallen humans are like under Adam’s headship, not what humanity is by definition. The Reformed do not teach two different human essences—one for Christ and one for us. They teach one shared humanity, with a different moral condition and representative relation: we are in Adam; Christ is not. The “lack” belongs to Adam’s original righteousness now forfeited and to our character under his verdict, not to the essence of humanity itself.

“The blindness analogy doesn’t hold. If every human were necessarily born blind, blindness would define the species as generated. That’s your model.”

Your own test defeats your claim: we do have humans with sight in the sample—Adam pre-fall, the glorified, and Christ. Therefore blindness (and by parity, sin) cannot be essential to the species; at most it is universal under a set of causes in a stage of history. The live question is necessary relative to what? It is necessary given that one is in Adam—then one sins. But Christ is not in Adam. The necessity is conditional (covenantal/order-of-history), not essential (species-defining).

“You reduce the issue to representation… Federal headship doesn’t explain why everyone is intrinsically incapable of good without regeneration. That incapacity is natural and unavoidable, not merely judicial.”

Headship explains both ground and effect. Adam’s act brings real guilt and the loss of original righteousness; the will is bent. That yields native inability in this economy—“native” meaning it comes with being born under the verdict, not that our essence has mutated. You’ve asserted that headship is insufficient, but that’s just the point at issue: my claim is precisely that Adam’s public person—by God’s ordering—is sufficient to account for both the forensic liability and the moral crookedness that follows.

“You also accuse me of denying that Christ and Adam are ontologically the same kind… I never said that.”

Good—we agree they’re both human. That’s exactly why Paul’s Second-Adam typology works: “since by a man came death, by a man came also the resurrection” (1 Cor 15:21). Christ is “made like His brothers in every respect—yet without sin” (Heb 4:15). Same essence; different headship and obedience. I raised the charge because your original use of 1 Cor 15 implied my view could not sustain Paul’s contrast; that implication collapses once we keep the categories straight: one humanity, two covenant heads—in Adam or in Christ.