The Necessity Problem — the short version

A high-level overview. If you want the full argument — the historical tables, the citations, the seventeen-century migration — the long essay is here.

Start here¶

Penal substitution needs God to be unable to simply forgive.

Not unwilling — unable. If God could have forgiven without the cross, then the cross wasn’t required, and everything built on top of it becomes decoration rather than structure. So something has to stand in the way. His justice, his holiness, his honour, his righteousness — the name varies. What doesn’t vary is that it has to be a genuine must.

Here is the whole objection in one sentence: that “must” is about our guilt, and our guilt didn’t exist until we made it.

Before the fall there was nothing for it to be about. Nothing obliged God to punish, because there was nothing to punish. After the fall, on this account, he cannot do otherwise. A constraint came to bind God that did not bind him before — and we are the ones who triggered it.

That is a very strange object to have inside God. And the striking thing about the history is that seventeen centuries of careful, serious people kept moving it around and never made it less strange. They adjusted where it lives and what kind of must it is. Nobody asked what it was about.

The step that gets skipped¶

There’s a move near the start of the argument that passes so smoothly almost nobody notices it happening.

You begin with something no one disputes: sin deserves punishment. That’s a claim about us. It’s about what a creature has earned.

What penal substitution actually needs is a different claim: God cannot leave sin unpunished. That’s a claim about God. It’s about what he is unable to do.

Those are not the same kind of statement, and getting from the first to the second is the entire problem. A fact about what a creature deserves has been converted into a limit on what the Creator is able to do. Everything below comes out of that one step.

Notice what the second claim is and isn’t doing. It isn’t what makes the cross matter — the church confessed the cross as the hinge of everything for a thousand years before anyone said God was unable to forgive without it. It’s what makes the cross matter penally. Remove it and the cross doesn’t become optional. It just stops being a payment.

Two addresses, both bad¶

Grant the step for a moment. You now have a must on your hands, and it has to be kept somewhere. There are only two directions.

Put it outside God — in the devil’s rights, in the moral order, in the demands of good government — and you’ve said that something which is not God now binds God. Every believer feels the problem with that immediately. It’s an insult to his sovereignty.

Put it inside God — in his essence, his nature, his character — and you protect his sovereignty at the cost of something else. Christians have always said that God has no unrealised potential: nothing in him is idling, nothing is waiting to be switched on later. He isn’t assembled out of parts, and he doesn’t change. Now put inside that God an attribute which is essential to him but has nothing whatever to do until a creature sins — and which switches on when one does.

Those two objections do not arrive on equal terms, and that asymmetry drives the entire history. Nothing outside God may bind God is available from day one and applies to every external address. The objections from God’s own nature only bite once the constraint is already inside, which means they always arrive late, against a position someone is already committed to.

So the constraint migrates. And it migrates one direction: inward.

Seventeen centuries, compressed¶

	Where the “must” is kept	What it costs
Athanasius, 4th c.	God’s truthfulness — he said death would follow, and he can’t go back on his word	Nothing yet. The binding is one God freely placed on himself
Ransom view, 3rd c.	The devil’s rights over captured humanity	Nothing in God — but the devil now has standing against him
Anselm, 1098	God’s honour, wounded by sin	A creature’s act now generates an obligation in God
Calvin, 1559	God’s justice. And the payment stops being a gift and becomes a penalty	Deferred. Calvin never says whether justice must punish or chooses to
Socinus, 1578	(the attack) Either God could have forgiven, so the cross was superfluous — or it was paid in full, in which case nothing was forgiven, it was collected	The tradition now has to say out loud where the must lives
Owen, 1647	God’s free decree. He chose this	Little — but only because something else is carrying the weight
Covenant view, c. 1648	A pre-creation contract between Father and Son	God now contracts with God
Owen, 1653	The divine essence. He reverses himself: God can no more leave sin unpunished than deny himself	An idle capacity inside a God who is supposed to have none
Owen, 1655	Split in two: that sin is punished is necessary; who, when and how is free	One attribute now running on two settings at once
Turretin, 1679–85	Split again, inside the attribute: God necessarily has the disposition, freely uses it	Names the idle capacity instead of removing it
Packer, 1973	Mystery. The must is still asserted; what grounds it is withdrawn from inspection	Intelligibility

The shape is unmistakable once you see it. First the must gets moved — five times, each time further in, until it reaches the divine essence and there is nowhere further in to go. Then the motion changes kind and the container starts getting split, twice, into ever smaller pieces. Then, when splitting stops helping, it evaporates. No splitting happens before the moving is exhausted. No moving happens after the splitting begins. That isn’t what a tradition wandering around looks like. It’s what a search space being used up in order looks like.

Owen is the hinge, twice over — he moves the must into the essence in 1653 and performs the first split two years later. He didn’t discover that necessity belonged in God’s essence and then separately discover it needed subdividing. He ran out of room and changed operations.

And here’s the part that should bother you most: in every single row, the thing the “must” is about is something we did. The devil’s captives, the offence against honour, the guilt, the debt, the foreseen elect. Nobody, in seventeen centuries, ever relocates that. All the ingenuity went into whether the must is absolute or conditional and whether it sits in God’s will or his nature. None of it went into what the must is about — which is where the trouble always was.

Worth noticing on the way past: the specifically penal element is the last piece to arrive. The transaction frame comes in the third century, the two-party debt frame in 1098, and the conversion of the payment from a gift into a penalty in 1559. Anselm’s satisfaction is explicitly what makes punishment unnecessary — it’s offered instead of the penalty. Penal substitution’s satisfaction is the penalty. Both camps use the word “satisfaction” for opposite mechanisms. And once the payment is a penalty rather than a gift, you need some way of getting the guilt onto the one who pays it, which is exactly why imputation gets invented when it does. It isn’t an independent discovery about scripture. It’s the bill that arrives with the penal turn.

None of this is a charge of bad faith. The people in that table weren’t sloppy; they were working hard to protect exactly the things a Christian should want protected, and their moves are ingenious. The same is true today. If you’ve defended PSA in conversation you may have noticed how easily the ground shifts — you answer one objection by leaning on God’s freedom, the next by leaning on his nature, and both answers feel right in the moment. That flexibility is where the doctrine gets its staying power, and it’s why the person questioning it usually senses something is off without being able to say what. It isn’t a trick. It’s what happens when a system has many available positions and no stable one. Eventually you accept it as mystery and assume it’s the only way it could work.

I was there myself.

“But mercy has no object either”¶

If you know any classical theology you’ve had the reply ready for a page or two now, and it’s a good one. God’s mercy had no object before creation either. Neither did his creative power, or his knowledge of what creatures would freely do. We handle this all the time: the change is in the creature, not in God. On that account Turretin’s split into having and using isn’t an improvisation at all — it’s standard equipment applied to a standard case. And if the objection works here, it works against every attribute of God that touches creation, which is far too much.

That reply is strong enough that the objection has to be sharpened. Two things sharpen it, and either one is enough on its own.

One: which way the causing runs. With creation, God acts and the creature exists as a result. Nothing a creature does compels anything in God. Nobody claims God must be merciful to this sinner rather than that one — mercy is a capacity awaiting a fitting occasion.

Retributive necessity runs the other way, and that’s its whole content: God cannot let sin go. A creature acts, and God is now required to respond in a way he isn’t free to withhold. That’s not an unexercised capacity. It’s a demand with a trigger, and the trigger is in our hand. The objection was never that God has idle equipment. It’s that we have a lever on him.

Two: what the concept needs in order to mean anything. Mercy and goodness are intelligible without creatures at all; the life of Father, Son and Spirit gives goodness an eternal object.

Retribution isn’t like that. It’s contrastive the way “cure” is contrastive. A cure isn’t merely unexercised in a world without disease — it’s unintelligible there. Retributive justice requires injustice in order to have any content whatsoever. So locating it in the essence of God isn’t locating an attribute that happens to lack an occasion. It’s locating in God a concept that can’t even be described without reference to a creature’s failure.

Put the two together and you get a sentence the doctrine has never been able to say out loud: on this account, we broke God when we sinned. Not damaged him. But a constraint came to bind him that hadn’t bound him before, and we’re the ones who pulled the lever.

One more, quickly. If justice-that-must-punish is an essential perfection, ask what’s missing in a world where nobody ever sins. Either nothing is missing — in which case it’s hard to see why it counts as an essential perfection, and the having/using split is doing no work. Or something is missing, in which case a sinless world is one where God is less fully displayed as what he is, and he has reason to want the fall. That second horn isn’t a smear; it’s a stated position in the tradition — Edwards argues that a full display of God’s perfections requires objects of both mercy and justice. But then God has authored the very condition that binds him, which makes the constraint self-imposed, and a self-imposed constraint isn’t a necessity at all. Socinus walks right back in.

The bill from the Trinity¶

One more cost, briefly, because it follows from the same move and is noticed least.

Once the obligation is inside God, the only parties left who can transact are the divine persons — which is exactly what shows up: a pre-creation covenant between Father and Son, the Son standing as guarantor, Christ presenting a payment to the Father. But a payment between two who share one essence, one will and one set of goods is in trouble whichever way you take it. If nothing really changes hands, the transaction is empty. If something really does, then one party gained what the other gave up, and they aren’t equal.

The usual answer is that the Son pays as man. But a finite nature can’t render infinite satisfaction — which is precisely why the tradition reached for the infinite worth of the divine person in the first place. Say his humanity has infinite value because it is the humanity of the divine person, and you’ve conceded it: the value is sourced in the divinity, and the payment is internal to God after all.

You can have an intelligible transaction, or you can have equality between the persons. Not both. And this isn’t speculation about where the logic leads — the modern fight over the Son’s eternal subordination is that logic surfacing under pressure.

Where it lands: mystery¶

By 1973 the answer becomes: this is a model, not a blueprint. It discloses something true about God without licensing us to press every joint of it.

Packer deserves better than a brush-off here — he’s doing serious philosophy of religious language, and his exegetical work is real. The point is narrower and more interesting than “he gave up.”

Of all the moving parts in the system, the one he declines to specify is the necessity. Not the transfer, not the proportion — the necessity. And you can see why. He can’t ground it in our sin without making the creature the author of an obligation in God. He can’t ground it in God’s essence without inheriting everything in the last two sections. Declining to say is the only remaining option that leaves the doctrine standing, which is why the silence falls exactly there and nowhere else.

That isn’t fatigue. It’s an accurate read of the terrain.

Why there’s nothing to house¶

Everything so far shows the doctrine can’t find a home for its central claim. But you could accept all of it and still say: fine, retribution is real, we’ve just been bad at explaining where it lives.

So here’s the further claim, and it’s the one that actually matters.

Ask what justice requires in an ordinary case. A child takes another child’s toy. Justice is served when the toy goes back. Not when the taker suffers proportionally — the suffering, where we impose it, is doing some other job: deterrence, or marking the wrong publicly, or vindicating the wronged child’s standing. The restoration is what makes the situation just. Everything else is commentary on it.

Now take a case where the thing can’t be given back. A murder. There is no act available to anyone that restores what was taken, because we can’t raise the dead and can’t turn back time. Justice in the proper sense is permanently off the table. What’s left is to display the justice we cannot perform — to mark, proportionally, that a wrong of this size occurred, and refuse to let it pass unmarked.

That’s a real and serious thing to do, not a fiction. But look at what generates the need for it. We reach for retribution exactly where restoration is impossible, and restoration is impossible because we are finite. The irreversibility, the residue no compensation reaches — those aren’t features of wrongdoing as such. They’re features of wrongdoing under our conditions, where time runs one way and the dead stay dead.

God is not under those conditions. Restoration is never unavailable to him. The resurrection isn’t a workaround for justice; it’s justice performed rather than displayed.

Which inverts the whole necessity claim. Owen’s argument is that God’s justice is so complete it cannot let sin pass unpunished. But retributive necessity isn’t a mark of justice’s completeness — it’s a mark of justice being obstructed. In us it registers a limit: this can’t be put right, so it must at least be marked. To make that limit essential to God is to write our finitude into his nature and call it a perfection.

That’s the real sense in which this is a foreign object. Not merely that the constraint has no coherent address, though it doesn’t. It’s that the thing being housed belongs to the moral life of beings who run out of options. Install it in a being who never runs out of options and it can only sit there as a stored demand waiting for a creature to pull the trigger — which is precisely what every position in that table was trying and failing to make sense of.

Two consequences worth sitting with.

The retributive God is the smaller God. The intuition usually runs the other way: strict justice sounds serious and demanding, restoration sounds like leniency. But strict retribution is what you fall back on when repair is beyond you. A God who must balance the books is a God for whom the alternative is closed.

And it explains why everyone who leaves leaves by the same door. Grotius makes the penalty relaxable. The New England Calvinists redefine justice as doing whatever best serves the moral order. Socinus and Kant never grant the necessity in the first place. Campbell and Torrance empty the slot entirely and go back to the Greek fathers. These people disagree with each other about nearly everything — the person of Christ, the authority of scripture, what the cross accomplishes. Structurally they make the same move four separate times: stop looking for somewhere to put the necessity. Which is also why the argument between them and PSA never resolves. They aren’t offering rival answers to “where does the necessity live.” They’re declining the question.

The verse you’re about to bring up¶

Romans 3:25–26 — Christ set forth to demonstrate God’s righteousness, so that he might be just and the justifier of the one who has faith. It’s the strongest evidence against everything here, and it’s entirely reasonable to read it as saying God’s own justice required the cross.

Two observations, neither a dismissal. The passage establishes a display of righteousness, publicly made; it doesn’t say whether the thing displayed was necessary, fitting, or freely chosen — and that is precisely the question at issue. And “just and the justifier” states a conjunction, not a mechanism. It says God is both. It doesn’t say what makes both possible, or that the second required a substitute’s penal suffering to make room for it. Reading the mechanism in is the interpretive tradition’s contribution, not the sentence’s.

The place a text-first conversation actually turns is hilastērion — whether it means the propitiation of wrath or the cleansing away of defilement. That can’t be settled from this direction.

What stands in its place¶

It would be reckless to take a doctrine apart and leave the ground bare, mostly because of who tends to be standing there.

The people this doctrine costs most are not the careless. It survives untroubled in anyone who holds it at arm’s length. It becomes unbearable precisely to the person who takes it seriously enough to feel it — who follows the transfer of guilt to its conclusion and asks what sort of Father requires the blood of his Son before he can look at his children without anger. That person is told to look at Jesus and see the Father, and when they do, they find someone unexpected standing behind him: a hidden God with a prior demand, whose disposition toward them had to be purchased before it could be enjoyed. They came for comfort and were handed a creditor. Many people I know and love have left the faith over exactly this. Many others have been brought to Christ through this doctrine and love God by it, and nothing here is aimed at them. But the wreckage is real, and it falls hardest on the tender and the scrupulous.

So: Athanasius already has a complete account, and it needs one repair. In On the Incarnation he sets up a divine dilemma — God’s goodness would redeem us, but his truthfulness can’t let the sentence of death go unfulfilled. That’s the one place he lodges a must in God, and it’s the seed of everything traced above. Prune it, and take instead his own better line a few pages later: death is what follows when a creature turns away from the source of its own life, the way cold follows the removal of heat. Not a sentence imposed from outside. What absence is.

Then the shape of the gospel changes. The problem was never that God’s books wouldn’t balance. The problem was that we were dying. Sin isn’t first a debt but a self-inflicted wound — a turning from the One who holds us in being, and the unravelling that follows. Nothing needed to be paid, because payment was never what the situation called for. What it called for was rescue.

And God came down himself. The Word through whom everything was made took on the very nature that was coming apart, carried it into death, and death couldn’t hold him — life of that kind can’t be contained by it. He didn’t talk the Father round, because there was nothing to talk him out of. He didn’t absorb a penalty, because a penalty was never hanging over us waiting to fall. He went down into the grave and broke it open from the inside, and the nature he carried through it is the nature you are wearing right now.

So what you’re offered is not a verdict but a life. Not being counted righteous while remaining exactly what you were, but actually healed. It is not a lighter gospel than the one it replaces. It’s a heavier one, because it proposes to change you rather than your paperwork.

The God at the end of it¶

Everything argued here about the doctrine of God turns, at the last, into good news.

Nothing in God is waiting to be switched on. No stored demand. No reserve of wrath held in check pending a trigger. Nothing latent in him that had to be discharged before he could turn his face toward you. No spring preloaded with guilt existed before creation. God is not assembled out of parts — his justice isn’t a second thing standing behind his love and negotiating terms with it. It’s an outflow of his infinitely self-giving love and it’s aim is restoration not destruction. There is no committee in God, no attribute that has to be satisfied before another is free to act. God does not change — he has not changed toward you and cannot. No shadow of turning. No God behind God.

He is not a creditor who was satisfied. He is not a judge who was talked round. He has been giving himself away since before the foundation of the world, Father to Son and Son to Father, and everything that exists is the overflow of it. Nothing changed in him when he made man. The cross was not the price of his affection. It was his affection, arriving where we were, going as far down as we had fallen and further, until there was nowhere left for a person to be lost and not found.

There is nothing behind Jesus but more of the same: the same light, further in, all the way to the core.