A one-line maxim, and the last thing James says before the invective of chapter 5. Grammatically it is simple: a dative participial phrase fronted, resumed by a dative pronoun, with an anarthrous predicate noun landing last but one. Everything hard about the verse is a question of scope and function, not of vocabulary.

Three things to see.

1. The proverb-shape. Nothing here is distinctively Christian vocabulary — no Christ, no law, no faith. It reads as a free-standing sapiential maxim, and it may well be one that James is quoting or adapting rather than coining. Its closest formal cousins are rabbinic and Hellenistic sayings about culpable knowledge, and its closest NT cousin is Luke 12:47.

2. οὖν is load-bearing and its scope is open. Does the ‘therefore’ draw the conclusion from the boasting merchants of vv. 13-16 (where the sin is a specific known omission — saying ‘if the Lord wills’), from the whole of chapter 4, or from the letter entire? The particle does not say, and the answer changes whether this is a targeted verdict or a general principle appended as a summary.

3. The definition is of sins of omission, and it is deliberately unqualified. James does not write ‘this too is sin’ or ‘it is also sin.’ He writes ἁμαρτία αὐτῷ ἐστιν, with the noun anarthrous and fronted. The verse says that knowing-and-not-doing is sin, full stop. Whether that is intended as a comprehensive definition of sin or as one case brought under the category is the verse’s chief exegetical pressure point, and no rendering should settle it.

The corpus policy on οὖν is settled: inferential, always rendered, never dropped (§10); ‘so then’ where it both infers and marks a discourse shift, bare ‘therefore’ for tight logical inference inside one argument. The difficulty at Jas 4:17 is not the gloss but the reach.

Rendering policy: ‘so then’ carries both the inference and the discourse shift and does not narrow the antecedent. Anything that specifies — ‘so then, as for these people’ — resolves in the reading text what the particle leaves open.

Built onbdf · bdag

Proposed — pending reviewRalph P. Martin, James, Word Biblical Commentary 48 (Waco, TX: Word Books, 1988).

οἶδα is already fixed in this corpus as ‘know’ — perfect in form, present in force, denoting settled knowledge rather than inference, and kept lexically distinct from γινώσκω (‘come to know’), ἐπίγνωσις (‘full knowledge’), and οἴομαι (‘suppose’). James himself uses the lemma at 1:19 (Ἴστε), 3:1 (εἰδότες), 4:4 (οὐκ οἴδατε), and 4:14 (οὐκ ἐπίστασθε, the near-synonym) — in every case of knowledge the addressees possess or ought to possess.

The force here is stative and settled: the person is not in the process of working out what is right. He has it. That is what makes the omission culpable rather than merely regrettable, and it is why the maxim cannot be applied to ignorance without dismantling it.

The dative is the case of the person to whom the predication holds (dative of reference or of disadvantage), fronted before the main clause. It has no verb of its own: the participles are substantival under a single article-less construction and the whole phrase is picked up by αὐτῷ.

One construction question worth flagging: εἰδότι καλὸν ποιεῖν could be read as οἶδα + infinitive, the standard Koine idiom for acquired competence (‘know how to’), already fixed in this corpus at Phil 4:12. On that reading the person knows how to do good. But καλόν stands as the object accusative of ποιεῖν, and the natural sense is ‘knows [what is] good to do’ — knowledge of the right course, not of the technique. The competence-idiom is available and should be noted; it is not the better reading, since the maxim is about obligation, not skill.

Built onbdag · bdf

καλός is fixed in the corpus as ‘good / honorably,’ with the standing rule that where καλός and ἀγαθός occur in adjacent contexts (Gal 6:9-10) the switch is recorded rather than manufactured in English. James uses both: καλῶς at 2:8 and 2:19, καλήν of ἀναστροφή at 3:13, ἀγαθῶν of fruits at 3:17. No stable Koine distinction between the two adjectives can be sustained, and none is asserted here.

The adjective is anarthrous and substantival — ‘[what is] good,’ not ‘the good.’ That matters: an articular τὸ καλόν would name a defined body of known obligation; the anarthrous form leaves the content open, case by case. James supplies no list. Whether the referent is the νόμος βασιλικός (2:8), the specific instruction of v. 15, or right action generally is left to the hearer, and that openness is part of the maxim’s reach.

ποιέω is the corpus’s ‘do,’ kept distinct from πράσσω (‘practice / carry out’), ἐργάζομαι (‘work [something]’), and ἔργον. James has built his letter on the ποιε- root: ποιητὴς λόγου / ποιητὴς ἔργου (1:22-25), ποιητὴς νόμου (4:11), ποίησις (1:25). The verb here is not an incidental choice — it closes the doer/hearer thread that opened at 1:22.

The infinitive is present, durative: doing good as a practice, not a single act. So too the participle ποιοῦντι in the second limb. The two must receive the same English root at both points, since the sentence is one verb twice — known and not done.

μή is the regular participial negative in Koine (BDF §430) and carries no independent weight — the corpus already fixes this. Nothing may be read out of the choice of μή over οὐ here.

Two features do carry weight.

First, the object of ποιοῦντι is unexpressed. Greek does not say what is not being done; the accusative καλόν governs only the infinitive in the first limb. English cannot leave a transitive ‘do’ dangling, so ‘it’ must be supplied — bracketed in the literal tier, unbracketed in reading tiers. Some later witnesses supply αὐτό, which is exactly the kind of clarification that shows the text’s own reticence.

Second, the two participles stand under one construction joined by καί, so the subject is one person described twice, not two people contrasted. The καί is plain coordination; the adversative sense (‘and yet’) comes from the collision of the two descriptions, not from the particle. English may mark it with ‘and yet’ or a dash in reading tiers, but the note must record that Greek supplies no adversative — James had δέ and ἀλλά available and used neither.

The force of the whole construction is what makes this a definition of sins of omission. Nothing bad is done. The offense is entirely constituted by the gap between settled knowledge and absent action.

Built onbdf

ἁμαρτία is anarthrous, fronted before the pronoun and the copula, and stands as predicate nominative to an unexpressed subject.

The anarthrous form is qualitative: sin, of that character — not ‘the sin’ (a specified offense) and not ‘a sin’ (one item in a list). English idiom permits the bare noun here and it should be kept bare: ‘it is sin.’ Supplying an indefinite article (‘it is a sin’) quietly converts a categorical predication into an enumeration, and supplying the definite (‘it is the sin’) narrows to a named offense.

The fronting is emphatic. Greek could have written ἐστιν αὐτῷ ἁμαρτία; the word actually written first after the participial phrase is the accusation. English word order cannot reproduce this without strain, so the emphasis is carried by placing ‘sin’ last in the clause, where English gives weight, and the fronting is recorded here.

James uses ἁμαρτία sparingly and always with real force (1:15 twice, 2:9, 4:17, 5:15, 5:20). Its cognates in the letter are ἁμαρτωλοί (4:8; 5:20). The corpus keeps ἁμαρτία distinct from παράπτωμα (‘trespass / false step’), παράβασις (‘transgression,’ a marked line crossed), and ἀδικία (‘unrighteousness’) — all of which James had available. The choice of the broadest term is deliberate: the verdict is not that this is a kind of failure but that it falls under the general category.

Rendering policy: the bare predicate ‘it is sin’ is as open as the Greek and is retained. ‘That is sin for him’ and ‘he is guilty of sin’ each shade the verdict — the second especially, since it substitutes a status-word for a category-word.

Built onbdag

Proposed — pending reviewPeter H. Davids, The Epistle of James: A Commentary on the Greek Text, New International Greek Testament Commentary (Grand Rapids: Eerdmans, 1982).

The dative pronoun αὐτῷ resumes the fronted dative participles εἰδότι … ποιοῦντι. By strict Attic standards it is pleonastic — the participles are already dative and need no pronoun to complete them.

This is not sloppiness. Resumption of a fronted constituent by a pronoun is good Koine and carries strong Septuagintal colouring, reproducing the Hebrew pattern in which a topicalized element is picked up by a resumptive suffix. The corpus already has a policy for the nominative version of this construction — casus pendens with a resumptive demonstrative (Phil 3:7) — and the same discipline applies here: preserve both the fronting and the resumptive pronoun. English can do this with a dash and a repeated pronoun: ‘to one who knows … and does not do it — to him it is sin.’

Deleting the resumption (‘whoever knows … and does not do it sins’) recasts the sentence as a subject-verb clause, which is precisely what James avoided. The dative construction places the person in the position of one to whom a verdict accrues rather than one who performs an act, and that framing is part of the maxim’s weight.

Whether the dative is one of reference (‘as concerns him, it is sin’), of disadvantage (‘it counts against him’), or of possession (‘it is his sin’) is not decidable and need not be. Plain English ‘to him’ holds all three.

Built onbdf

The verse is textually quiet. NA28 prints it without variation in the outer apparatus, and the reading is uniform across the major witnesses (𝔓⁷⁴ vid, א, A, B, C, P, Ψ, and the Byzantine tradition).

Minor scribal activity that does appear runs in the predictable direction of clarification rather than of change:

• Supplying an object for the second participle (αὐτό after ποιοῦντι) in a small number of minuscules — filling the gap the Greek deliberately leaves.
• Occasional transposition around αὐτῷ ἐστιν, again a smoothing of the resumptive redundancy.

Neither affects the sense, and neither is adopted. What both illustrate is that the two features a translator is most tempted to repair — the unexpressed object and the pleonastic resumptive pronoun — were felt as rough by ancient copyists too, which is a reason to keep them visible rather than to smooth them (§4).

Built onna28 · metzger-tc

Vulgate: Scienti igitur bonum facere et non facienti, peccatum est illi. An exact calque — datives fronted, resumptive illi retained, peccatum anarthrous. Jerome reproduces the Greek construction, including the redundancy, which is worth recording as a check on English versions that tidy it away.

Peshitta likewise preserves the participial datives and the resumption, which the Syriac construction accommodates more comfortably than Latin or English.

Patristic reading. The Greek commentators take the verse as a general maxim on sins of omission rather than as a verdict confined to the merchants — which is evidence for the broad reading of οὖν, though it is reception rather than lexical evidence (§11). The verse became a standard proof-text in later moral theology for the category of peccatum omissionis, and that downstream use has shaped English renderings toward ‘it is a sin’ (enumerative, one offense among many) rather than ‘it is sin’ (categorical). Per §11 the resonance may be named but supplies no evidence for the rendering: the anarthrous predicate decides it.

Augustine’s use of the verse to press the depth of human liability, and the corresponding patristic care to hold it together with Luke 12:47-48’s graded culpability, both belong to reception and are recorded rather than built into the text.

Proposed — pending reviewDale C. Allison Jr., A Critical and Exegetical Commentary on the Epistle of James, International Critical Commentary (London: Bloomsbury T&T Clark, 2013).

The sentence is a maxim, and the whole apparatus of James’s paraenesis pauses for it. There is no vocative (contrast 4:11, 4:13; 5:1), no imperative, no second person at all — the letter’s most sustained direct address gives way to a third-person generalization, and then chapter 5 resumes the assault.

Formally it belongs to the wisdom tradition: a conditional-participial protasis, a bare predicate apodosis, no connectives beyond οὖν and καί. James writes this way elsewhere (1:12; 2:13b; 3:18; 5:20), and in each case the sentence can stand alone. That detachability is why the verse has always travelled well as a quotation — and why its context has always been contested.

Two consequences for rendering, per §10. The terseness is preserved: no explanatory expansion, no supplied subject beyond the grammatically necessary ‘it,’ no softening qualifier. And the impersonal third-person form is kept — converting to a second person (‘if you know the right thing to do…’) would make the maxim an accusation and erase the shift in grammatical person that is the verse’s most conspicuous formal feature.

Proposed — pending reviewMartin Dibelius, James: A Commentary on the Epistle of James, rev. Heinrich Greeven, Hermeneia (Philadelphia: Fortress Press, 1976).