Hebrews 3:12

Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God.

EXPOSITORY (ENGLISH BIBLE)

Ellicott's Commentary for English Readers

(12) Lest there be in any of you.—Better, lest haply there shall be in any one of you. (See above, on Hebrews 3:7.)

In departing.—Better, in falling away from a Living God. The heart of unbelief will manifest its evil in apostasy. The Greek word apistia stands in direct contrast to “faithful” (pistos), Hebrews 3:2, and combines the ideas of “unbelief” and “faithlessness.” He whose words they have heard is a living God, ever watchful in warning and entreaty (Hebrews 3:8), but also in the sure punishment of the faithless (Hebrews 3:11; Hebrews 10:31).

Benson Commentary

Hebrews 3:12-13. Take heed — Βλεπετε, see to it, consider, use care and circumspection; brethren, lest — Μηποτε, lest at any time; there be in any of you — As there was in your forefathers of old; he speaks to them collectively, to take care that none might be found among them with such a heart as he guards them against, and consequently his caution concerned every individual of them; an evil heart of unbelief — Unbelief is the parent of all evil, and the very essence of it lies in departing frown God, as the living God — The fountain of all our life, holiness, and happiness. For as faith draws near to him in the consideration and knowledge of him, in beholding his glory, in desire after him, gratitude to him, and delight in him; continually aspiring after a conformity to him, and longing to enjoy union and communion with him; so unbelief produces directly contrary effects, rendering the mind averse to approach God in these respects and for these purposes, disliking and shunning all intercourse with him. It is distinguished by some into negative and positive. Negative unbelief is wherever any believe not, or have not faith, because they have not yet had the means of believing, namely, the Scriptures, or the truths declared in them, as the heathen nations. Such, supposing they believe and lay to heart the truths of what is called natural religion, cannot be said to have in them an evil heart of unbelief. 2d, Positive unbelief is where men believe not, though they enjoy the means of faith. This latter is here meant, and in it consist some of the highest workings of the depraved nature of man; it being, on many accounts, the greatest provocation of God that a creature can be guilty of. For it is an opposition to God in all the perfections of his nature, and in the whole revelation of his will. And therefore the gospel, which is a declaration of grace, mercy, and pardon, and which indeed condemns all sin, yet denounces final condemnation only against this sin, he that believeth not shall be damned, Mark 16:16.

Observe reader, the apostle’s caution against a heart of unbelief implies two things: 1st, That we take heed lest, through refusing to consider the evidence of the truth, or the goodness and excellence of the things proposed to be embraced by our faith, we should continue in our natural unbelief, and never attain faith. 2d, Lest we should reject or decline from the faith after it has been received, through neglect of the means which minister to its continuance and increase, namely, the word of God, prayer, Christian fellowship, the Lord’s supper, &c.; through yielding to the temptations of the devil, the world and the flesh, and to the love of sin; through unwatchfulness and the neglect of self-denial and mortification; through relapsing into our former habits, and imitating the spirit and conduct of the carnal and worldly part of mankind around us; — through fear of reproach, of ill-usage and persecution from those that are enemies to the truth and grace of God. As a powerful means to prevent this from being the case, the apostle adds, exhort one another, &c. — It is justly observed by Dr. Owen, that “many practical duties are neglected because they are not understood, and they are not understood because they are supposed to have no difficulty in them.” The duty of constant exhortation, that is, of persuading men to constancy and growth in faith, love, and obedience, to watchfulness and diligence in the ways of God, and attention to every duty which we owe to God, our neighbour, and ourselves, is the most important part of the ministerial office. It is, however, not confined to ministers: it must also be mutual among believers; and, in order to the right performance of it, the following things are necessary: 1st, A deep concern for one another’s salvation and growth in grace. 2d, Wisdom and understanding in divine things. 3d, Care that only words of truth and soberness be spoken, for only such words will be attended with authority, and have the desired effect. 4th, Avoiding those morose and severe expressions which savour of unkindness, and using words of mildness, compassion, tenderness, and love, at least toward such as are well- disposed, and desirous to know and do the will of God. 5th, Avoiding levity, and always speaking with seriousness. 6th, Attention to time, place, persons, occasions, circumstances. 7th, A suitable example in the persons exhorting, giving weight and influence to every advice that is given, in imitation of the apostle, who could say, Be ye followers of me as I am of Christ. 8th, We must be unwearied in this duty, and exhort one another daily; and that not only in appointed meetings, but in every proper season, and on all fit occasions, whenever we happen to be in company one with another: and, lastly, while it is called today — While the season for doing it continues; and therefore now, without delay, the time for performing this duty being both very short and very uncertain.

As a motive impelling to the practice recommended, the apostle adds, lest any of you be hardened — That Isaiah , 1 st, Rendered blind and insensible as to the nature, excellence, necessity, and importance of spiritual things: 2d, impenetrable to mercy or justice, promises or threatenings; to the word, providence, or grace of God; stubborn and irreclaimable: 3d, Abandoned, and finally given up of God to sin and its consequences. It should be well observed, that this awful effect is not usually produced suddenly, and all at once, but by slow degrees, and perhaps insensibly, just as the hand of a labouring man is wont gradually to contract a callousness. It is effected, the apostle says, by the deceitfulness of sin, probably first by yielding to, instead of resisting and mortifying, sinful dispositions and corrupt passions, which by degrees produce those sinful practices, which, 1st, Not only grieve, but quench and do despite to the Spirit of grace, and cause him to withdraw his influences from us. 2d, The mind becomes hereby indisposed, and averse to attend to, or to obey, the voice of God in his word or providence, to consider or to yield to his counsel and authority. Hereby, 3d, The conscience is stupified, the will, affections, and all the powers of the soul are preoccupied and engaged in the service of sin and Satan, of the world and the flesh. The apostle terms sin deceitful, because it promises the satisfaction it never yields: persuades us we may venture to yield a little to its solicitations, but need not go far; — that we may yield at this time, this once, but need not afterward; — that we may and can repent and reform when we will; — that God will not be extreme to mark little things; — and that he is merciful, and will not be so strict as ministers are wont to urge, in fulfilling his threatenings.

Matthew Henry's Concise Commentary

3:7-13 Days of temptation are often days of provocation. But to provoke God, when he is letting us see that we entirely depend and live upon him, is a provocation indeed. The hardening of the heart is the spring of all other sins. The sins of others, especially of our relations, should be warnings to us. All sin, especially sin committed by God's professing, privileged people, not only provokes God, but it grieves him. God is loth to destroy any in, or for their sin; he waits long to be gracious to them. But sin, long persisted in, will make God's wrath discover itself in destroying the impenitent; there is no resting under the wrath of God. Take heed: all who would get safe to heaven must look about them; if once we allow ourselves to distrust God, we may soon desert him. Let those that think they stand, take heed lest they fall. Since to-morrow is not ours, we must make the best improvement of this day. And there are none, even the strongest of the flock, who do not need help of other Christians. Neither are there any so low and despised, but the care of their standing in the faith, and of their safety, belongs to all. Sin has so many ways and colours, that we need more eyes than ours own. Sin appears fair, but is vile; it appears pleasant, but is destructive; it promises much, but performs nothing. The deceitfulness of sin hardens the soul; one sin allowed makes way for another; and every act of sin confirms the habit. Let every one beware of sin.

Barnes' Notes on the Bible

Take heed, brethren - In view of the conduct of the rebellious Jews, and of their fearful doom, be on your guard lest you also be found to have had the same feelings of rebellion and unbelief. See to it, that under the new dispensation, and in the enjoyment of the privileges of the gospel, you be not found to manifest such feelings as shall exclude you from the heavenly world. The "principle" has been settled by their unbelief that they who oppose God will be excluded from his rest. That may be shown under all dispensations, and in all circumstances, and there is not less danger of it under the gospel than there was when the fathers were conducted to the promised land. You are traveling through a wilderness - the barren wilderness of this world. You are exposed to trials and temptations. You meet with many a deadly and mighty foe. You have hearts prone to apostasy and sin. You are seeking a land of promise; a land of rest. You are surrounded by the wonders of Almighty power, and by the proofs of infinite beneficence. Disobedience and rebellion in you will as certainly exclude you from heaven as their rebellion did them from the promised land; and as their great sin was unbelief, be on your guard lest you manifest the same.

An evil heart of unbelief - An evil, unbelieving heart. The word "unbelief" is used to qualify the word "heart," by a Hebraism - a mode of speech that is common in the New Testament. An unbelieving heart was the cause of "their" apostasy, and what worked their ruin will produce ours. The root of their evil was "a want of confidence in God" - and this is what is meant here by a heart of unbelief. The great difficulty on earth everywhere is a "want of confidence in God" - and this has produced all the ills that man has ever suffered. It led to the first apostasy; and it has led to every other apostasy - and will continue to produce the same effects to the end of the world. The apostle says that this heart of unbelief is "evil." Men often feel that it is a matter of little consequence whether they have faith or not, provided their conduct is right; and hence, they do not see or admit the propriety of what is said about the consequences of unbelief in the Scriptures. But what do they say about a want of confidence between a husband and wife?

Are there no evils in that? What husband can sleep with quietness on his pillow, if he has no confidence in the virtue of his wife? What child can have peace who has no confidence in a parent? How can there be prosperity in a community where there is no confidence in a bank, or an insurance office, or where one merchant has no confidence in another; where a neighbor has no confidence in his neighbor; where the sick have no confidence in a physician, and where in general all confidence is broken up between man and man? If I wished to produce the deepest distress in any community, and had the power, I would produce the same want of confidence between man and man which there is now between man and his Maker. I would thus take away sleep from the pillow of every husband and wife; every parent and child; and make every man wretched with the feeling that all the property which he had was insecure. Among people, nothing is seen to be productive of greater evil than a want of confidence or faith - and why should not the same evil exist in the divine administration? And if want of confidence produces such results between man and man, why should it not produce similar, or greater, miseries where it occurs in relation to God? There is not an evil that man endures which might not be alleviated or removed by confidence in God; and hence one great object of the Christian religion is, to restore to man his lost confidence in the God that made him.

In departing from the living God - Manifested in departing from him; or leading to a departure from him. The idea is, that such a heart of unbelief would be connected with apostasy from God. All apostasy first exists in the heart, and then is manifested in the life. They who indulge in unbelief in any form, or in regard to any subject, should remember that this is the great source of all alienation from God, and that if indulged it will lead to complete apostasy. They who wish to live a life of piety should keep the heart right. He that lives "by the faith of the Son of God" is safe; and none is safe but he.

Jamieson-Fausset-Brown Bible Commentary

12. Take heed—to be joined with "wherefore," Heb 3:7.

lest there be—Greek (indicative), "lest there shall be"; lest there be, as I fear there is; implying that it is not merely a possible contingency, but that there is ground for thinking it will be so.

in any—"in any one of you." Not merely ought all in general be on their guard, but they ought to be so concerned for the safety of each one member, as not to suffer any one to perish through their negligence [Calvin].

heart—The heart is not to be trusted. Compare Heb 3:10, "They do always err in their heart."

unbelief—faithlessness. Christ is faithful; therefore, saith Paul to the Hebrews, we ought not to be faithless as our fathers were under Moses.

departing—apostatizing. The opposite of "come unto" Him (Heb 4:16). God punishes such apostates in kind. He departs from them—the worst of woes.

the living God—real: the distinctive characteristic of the God of Israel, not like the lifeless gods of the heathen; therefore One whose threats are awful realities. To apostatize from Christ is to apostatize from the living God (Heb 2:3).

Matthew Poole's Commentary

Here the Spirit applieth the former dreadful example of sin and judgment to the Hebrews, to forewarn them how they sinned as these did, lest they partake of the like vengeance; and so enters his caution against unbelief.

Take heed, brethren: Blepete signifies not an act of sight, but of the mind, circumspection, watchfulness, and heed, taking exactest caution of the evil forbidden, Hebrews 12:15,25 1 Corinthians 8:9.

Brethren they were to Paul in the flesh, and more so as true believers in Christ; he cautions them particularly, one by one, lest any root of bitterness should be amongst them, Hebrews 12:15.

Lest there be in any of you an evil heart of unbelief: the heart is the first, and proper, and chief subject, wherein all sin riseth, and from thence issueth into words and works, Matthew 15:18,19; compare Jam 1:14,15. This comprehendeth the mind, will, and affections, the whole inward man: and this heart in every man is naturally and habitually evil, continually forging and framing of it, Genesis 6:5; compare Jeremiah 17:9. Almighty grace only can change this heart; yet it works by counsel, and makes the soul willing to use the means appointed to effect it.

Unbelief, though but in itself, is but a denial to assent to or rely on the will of God revealed to it, yet is the spring and fountain of all other sin, the teeming womb from whence all issueth, as uncleanness, idolatry, unrighteousness, superstition, &c. It was the hardening sin of their forefathers, they would not believe, and then did murmur and rebel. It is the root of apostacy; men breaking their covenant with God in Christ, do then desert him. Against this perfidious, impious, perverted temper doth he caution them to watch, that neither for measure, nor season they ever do admit or allow it; that there be not at all in the least degree, or at any time, such a base, malignant quality in their hearts, Romans 11:20,21.

In departing from the living God; turning away, standing off, and separating the heart; it implies in it a real, total, final defection; actual and formal apostacy from him whom they had owned and received; and is actual rebellion against their lawful Sovereign, by turning either Jews or heathens, and renouncing the Christian religion and its Author; who is the living God, not only formally, as opposed to dead idols, but efficiently the Author and Fountain of all sorts of life, but especially of spiritual and eternal life, John 5:19-21,25,26: which living God is our Lord Jesus Christ, Hebrews 3:7, whose voice they were to hear, who was tempted by their unbelief in the wilderness, 1 Corinthians 10:9, who gave the law to them at Sinai, Hebrews 12:26. So that to apostatize from him and his religion, is to apostatize from God, and to renounce eternal life, and to subject themselves to eternal punishments, which he ever liveth to inflict on them. Unless they took heed to avoid this unbelief, it was impossible for them to persevere in Christianity, when threatened with persecutions, and the loss of peace, liberty, safety, estates, honours, relations, and life itself for it.

Gill's Exposition of the Entire Bible

Take heed, brethren,.... This exhortation is grounded upon the state and case of their ancestors before given, as a warning and caution to the then present Hebrews; and whom the apostle styles "brethren", to show that he had no hard thoughts of them, and that his jealousy was a godly one, and not an evil suspicion; and may teach us that all exhortations, admonitions, and reproofs should be given in love:

lest there be in any of you an evil heart of unbelief; or such an evil heart, in which unbelief prevails, and is predominant: there is in every man, whether a profane sinner, or an hypocritical professor, an evil heart, and an unbelieving one; and there is unbelief in regenerate persons, which when cherished and encouraged by them is a great evil, and should be avoided; and this sin is aggravated by the many instances of God's grace, and by the many declarations of it, and by the exceeding great and precious promises God has made, and by the great discoveries of his love to their souls in times past: and this sin, when it gets ahead, has a very great influence on the heart, to make it evil; and unbelief was the first sin of man, at least it very early appeared; it is the mother sin, and puts persons upon every sin; it defiles the conscience, hardens the heart, renders the word unprofitable, unfit for duty and makes men unstable, and therefore to be shunned; and especially because of the dreadful effect following:

in departing from the living God; that is, from Christ, who is the Son over his own house, and whose voice is to be heard; for of no other is the apostle speaking in the context; and who is not only the Son of the living God, but he is himself the living God; he is life in himself, and is the fountain and author of life, natural, spiritual, and eternal. This is mentioned to exalt the person of Christ, the apostle and high priest of our profession; and to discover the greatness and heinousness of the sin of such as depart from him and his Gospel, and to deter men from it: there is a final and total departure from Christ, from his Gospel and ordinances, from his people, and from a former profession of faith, which is never to be found in true believers; for they are as Mount Zion, which can never be removed; but there is a partial departure, and for a while, which they are liable to, and is attended with bad effects to them, and should be guarded against: saints should take heed of themselves, and of their hearts, and of the unbelief of them, that they do not in the least depart from Christ, by letting go their hold of him, or by a non-exercise of faith upon him; and this should be the care and concern of every individual member of the church, and at all times; unbelief is very dishonourable to God and Christ; contradicts the word and promises of God; is uncomfortable to the saints; it is a sin that very easily besets, and is very provoking to God, and is highly resented by him.

Geneva Study Bible

{7} Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God.

(7) Now consider in the words of David, he shows first by this word today that we must not ignore the opportunity while we have it: for that word is not to be limited to David's time, but it encompasses all the time in which God calls us.

EXEGETICAL (ORIGINAL LANGUAGES)

Meyer's NT Commentary

Hebrews 3:12-13. Close of the period begun with διό, Hebrews 3:7.

βλέπετε] beware, take heed.

μή ποτε ἔσται] μή after βλέπε, ὅρα, and similar words, with the indicative future (comp. Colossians 2:8), expresses at the same time with the warning, the fear that the warning will be slighted. Comp. Winer, Gramm., 7 Aufl. p. 468 f.; Hartung, Partikellehre, II. p. 140. The enclitic ποτε appended to the μή, not: at any time (Beza and others), but: haply [Hebrews 2:1; Luke 14:29; Acts 5:39; Matthew 4:6, etc.].

ἔ τινι ὑμῶν] different from ἐν ὑμῖν. Calvin: Nec tantum in universum praecipit apostolus, ut sibi omnes caveant, sed vult ita de salute cujusque membri esse sollicitos, ne quem omnino ex iis, qui semel vocati fuerint, sua negligentia perire sinant. Comp. Hebrews 3:13; Hebrews 10:24; Hebrews 12:15.

καρδία πονηρὰ ἀπιστίας] an evil heart of unbelief; comp. Hebrews 4:2-3. Wrongly Schulz and others: of faithlessness or ἀπείθεια, Hebrews 4:6; Hebrews 4:11, Hebrews 3:18; for the latter is only the consequence of the ἀπιστία. ἀπιστίας is either genitive of origin, which proceeds from unbelief (Owen, Bleek, Stengel, and others), or genitive of result, which leads to unbelief, renders inclined to the same (de Wette, Bisping, al.), or genitive of reference to a more precise characterization of πονηρά: a heart evil (on account) of unbelief, which is then equivalent to καρδία πονηρίαν ἀπιστίας ἔχουσα (so Winer, Gramm., 7 Aufl. p. 183; Ebrard, Alford, Meyer, Moll, and Hofmann). The last acceptation is to be preferred, since thereby ἀπιστίας is more clearly brought out as the main idea (for καρδία πονηρά is only a clothing of the same attaching itself to ἀεὶ πλανῶνται τῇ καρδίᾳ, Hebrews 3:10).

ἐν τῷ ἀποστῆναι ἀπὸ θεοῦ ζῶντος] more precise definition[60] to ἈΠΙΣΤΊΑς for the declaration of the outward form of appearance, in which the inner unbelief comes forth: in the falling away from the living God, or in such wise that a falling away from the living God takes place. God (not Christ: Gerhard, Dorscheus, Calov, S. Schmid, Schöttgen, Carpzov, al.) is called living, not in opposition to the dead works of the law (Hebrews 9:14, Hebrews 6:1; Bleek), nor in opposition to the idols of the heathen, similarly as 2 Kings 19:16, 1 Thessalonians 1:9, 2 Corinthians 6:16, Acts 14:15 (Böhme and others),—both of which must have been suggested by the context,—but because He does not allow His declared will to be slighted with impunity. Comp. Hebrews 10:31. That which is meant is the relapse from Christianity into Judaism. Limborch: Defectio hic intelligitur a religione Christiana; quia enim illa continetur ultima ac perfecta Dei voluntas, hinc sequitur, quod is, qui a religione Christiana deficit, ab ipso Deo deficiat. Ergo quicunque deserta fide Christiana ad Judaismum redeunt, a Deo deficiunt; licet enim Deum non abnegent, qui legis Mosaicae auctor est, tamen, quia Deus nunc non secundum legis praecepta se coli velle testatur, sed juxta evangelium illique credentibus fidem in justitiam imputaturum, etiam, qui illud deserunt, a Deo deficere dicendi sunt. Deus enim multis ac evidentissimis signis ac miraculis se Christum misisse ostendit, et voce e caelo demissa testatus est eum esse suum filium, in quo sibi complacuit jussitque ut eum audiant. Ergo praecepta ejus sunt praecepta Dei, etc.

[60] Schlichting: Duplex est enim incredulitas; una eorum, qui nunquam Deo credunt; altera eorum, qui credere desinunt, h. e. a Deo desciscunt seu apostatae fiunt.

Expositor's Greek Testament

Hebrews 3:12. Βλέπετε ἀδελφοὶ μή ποτε.… “Take heed lest haply” as in Hebrews 12:25, Colossians 2:8, for the more classical ὁρᾶτε μὴ. It is here followed by a future indicative as sometimes in classics. ἔν τινι ὑμῶν, the individualising, as in Hebrews 3:13 indicates the writer’s earnestness, whether, as Bleek supposes, it means that the whole Christian community of the place is to be watchful for the individual, may be doubted; although this idea is confirmed by the παρακαλεῖτε ἑαυτοὺς of Hebrews 3:13. What they are to be on their guard against is the emergence of καρδία πονηρὰ ἀπιστίας ἐν … ζῶντος, a wicked heart of unbelief manifesting itself in departing from Him who is a living God. ἀπιστίας is the genitive of quality = a bad, unbelieving heart; whether the wickedness proceeds from the unbelief, or the unbelief from the wickedness, is not determined. Although, from the next verse it might be gathered that unbelief is considered the result of allowed sin: i.e., it is when the heart is hardened through sin, it becomes unbelieving, so that the psychological order might be stated thus: sin, a deceived mind, a hardened heart, unbelief, apostasy. The main idea in the writer’s mind is that unbelief in God’s renewed offer of salvation is accompanied by and means apostasy from the living God. In the O.T. Jehovah is called “the living God” in contrast to lifeless impotent idols, and the designation is suggestive of His power to observe, visit, judge and succour His people. In this Epistle it occurs, Hebrews 9:14, Hebrews 10:31, Hebrews 12:22. To object that the apostasy of Jews from Christianity could not be called “apostacy from God” is to mistake. The very point the writer wishes to make is just this: Remember that to apostatize from Christ in whom you have found God, is to apostatize from God. It is one of the ominous facts of Christian experience that any falling away from high attainment sinks us much deeper than our original starting point.

Cambridge Bible for Schools and Colleges

12. Take heed, brethren, lest there be …] It is evident that deep anxiety mixes with the warning.

in any of you] The warning is expressed indefinitely; but if the Epistle was addressed to a small Hebrew community the writer may have had in view some special person who was in danger (comp. Hebrews 10:25, Hebrews 12:15). In any case the use of the singular might lead to individual searching of hearts. He here begins a homily founded on the quotation from the Psalm.

an evil heart of unbelief] Unbelief has its deep source in the heart more often perhaps than in the mind.

in departing] Lit., in the apostatising from. In that one word—Apostasy—the moral peril of his Hebrew readers was evidently summed up. To apostatise after believing is more dangerous than not to have believed at all.

from the living God] The epithet is not idle. It conveys directly the warning that God would not overlook the sin of apostasy, and indirectly the thought that Christ was in heaven at the right hand of God.

Bengel's Gnomen

Hebrews 3:12. Βλέπετε) This word depends on διὸ, wherefore, Hebrews 3:7 : the Apodosis here to Hebrews 3:7 [where see the note] not incorrectly also brings in the word brethren; 1 Thessalonians 3:7. The same word is found at ch. Hebrews 12:25. We must not trust to the heart; Jeremiah 17:9.—μή ποτε—ἀπιστίας, lest—of unbelief) Observe the connection. Christ is πιστὸς, faithful, Hebrews 3:2; therefore we ought to be πιστοὶ, faithful to Him, not unfaithful (unbelievers), as our fathers were in regard to Moses; Hebrews 3:18-19, ch. Hebrews 4:2-3, Hebrews 6:12. In like manner Paul places in opposition the faithfulness of God and the faithlessness of men, Romans 3:2-3; 2 Timothy 2:13.—ἔσται, lest there should be) Care must also be extended to the future on account of the greatness of the danger. He uses the fut. indic. in preference to the pres. subj.—πονηρὰ, evil) An ἄπιστος, unbelieving people; רע an evil nation and unhappy; comp. κακοὒς κακῶς, Matthew 21:41.—ἐν τῷ ἀποστῆναι, in departing) The antithesis is προσερχώμεθα, let us come unto, ch. Hebrews 4:16, and ὑποστασεώς, substance [i.e. solid confidence], presently at Hebrews 3:14; comp. Jeremiah 6:8, μὴ ἀποστῇ ὴ ψυχή μου ἀπὸ σοῦ, let not my soul depart from thee. This whole passage of the apostle agrees with Jeremiah 17:5-6 : ΕΠΙΚΑΤΑΡΑΤΟΣ ὁ ἄνθρωπος, ὅς τὴν ΕΛΠΙΔΑ ἔχει ἐπʼ ἄνθρωπον—καὶ ΑΠΟ ΚΥΡΙΟΥ ΑΠΟΣΤΗ ἡ καρδία αὐτοῦ—οὐκ ὄψεται ὄταν ἔλθῃ τὰ ΑΓΑΘΑ. CURSED is the man who TRUSTETH in man, and whose heart DEPARTETH from the LORD: he shall not see when GOOD cometh.—ἀπὸ Θεοῦ ζῶντος, from the living God) The life of GOD most powerfully and effectually animates our faith. The living God is also praised, ch. Hebrews 9:14, Hebrews 10:31, Hebrews 12:22. He who revolts from Christ, revolts from GOD; ch. Hebrews 3:12-19. Chiasmus.

13. Ἑαυτοὺς, yourselves) Let every one exhort himself and another; so far ought you to be from instigating and provoking one another [to unbelief].—ἡμέραν, σήμερον, daily, to-day) Conjugates; ch. Hebrews 4:7.—ἄχρις οὗ, whilst) as long as. This to-day will not continue for ever.—τὸ) the relative.—καλεῖται, is called) while that psalm is heard and read.—ἵνα μὴ σκληρυνθῇ τις, that no one be hardened) This is repeated from Hebrews 3:8.—ἀπάτῃ, through the deceitfulness) This corresponds to πλανῶνται, they err, Hebrews 3:10.—τῆς ἁμαρτίας, of sin) ἀπιστία, ἁμαρτία, unbelief and sin, which are much the same thing, John 16:9; Nehemiah 6:13 : where ἀπιστία and ἁμαρτία are mentioned together, they differ as species and genus; and unbelief, as the principal species of sin, has in its nature something more sad and destructive. But if sin be put by itself, the genus ἁμαρτία is contracted into this particular species, namely, unbelief: as ἁμαρτία is properly, when the main aim is missed, which is a result produced in the greatest degree through unbelief, ἀπιστίαν, in consequence of the grace of God having been neglected.16

Pulpit Commentary

Verse 12. - Take heed (literally, see), brethren, lest haply there should be (literally, shall be) in any one of you an evil heart of unbelief, in falling away from the living God. Here begins definitely the hortatory application of the warning of the ninety-fifth psalm. Its drift, to the end of the chapter, is: You, being called under the SON to a far higher position than your fathers under Moses were, but the retention of your position being, as theirs was, conditional on your faithfulness, see that you do not forfeit it, as some of you may be in danger of doing. That you may, if you are not careful, is shown by the very warning of the psalm, and by the example of your fathers, referred to in the psalm, all of whom, though called, failed of attainment through unbelief. It is implied all along that the "today" of the psalm includes the present day of grace, and points to a truer rest than that of Canaan, still offered to the faithful. But the full bringing out of this thought is reserved for the next chapter. On the language of ver. 12 we observe:

(1) The same form of warning, βλέπετε μὴ, occurs infra Hebrews 12:25, but then, suitably to the context, followed by a subjunctive. Here the future indicative which follows, μήποτε ἔσται, denotes a fact in the future, distinctly apprehended as possible (cf. Colossians 2:8). It had not ensued as yet, nor does the writer anticipate the probability of its being the case with all his readers; but in the state of feeling with regard to the gospel among the Hebrew Christians which the whole Epistle was intended to counteract, he sees ground for fearing it in the case of some. Their present wavering might result in apostasy.

(2) It is not necessary to analyze the expression," an evil heart of unbelief," so as to settle whether the evil heart is regarded as the result of unbelief, or unbelief of the evil heart; the main point to be observed is that unbelief is connected with moral culpability, as is implied further in ver. 13. The unbelief so condemned in Holy Scripture is not mere intellectual incapacity; it is condemned only so far as man is responsible for it on account of his own willful perversity or carelessness.

(3) The outcome of such "evil heart of unbelief," if allowed to become fixed and permanent, will be apostasy (ἀπόστηναι: cf. Luke 8:13; 1 Timothy 4:1) from "the living God," from him who is Eternal Life and the Source of all life and salvation. The thought of the momentous consequence of the falling away of Christians after light enjoyed is prominent in the Epistle (see especially Hebrews 6:4, etc.; Hebrews 10:26, etc.). The expression," the living God," further directs attention to the revelation of God in the Old Testament, in which he is continually so designated, and to the thought that it is the same God who has revealed himself finally in the SON. Addressing Hebrew Christians, the writer may mean to say," In apostatizing from Christ you would be cutting yourselves off from the God of your whole ancestral faith." There may be an intended allusion, too, to the oath, already referred to, of Numbers 14:21, 28, the form of which in the original is," As I live" (ζῶ ἐγὼ λέγει Κύριος, LXX.). Hebrews 3:12

Vincent's Word Studies

Note how the following exhortation is colored by the O.T. citation: evil heart; the to-day; be hardened; take heed (βλέπετε). See to it. Often in warnings or admonitions: sometimes with ἀπὸ from, with genitive of that against which the warning is given, as Mark 8:15; Mark 12:38; but so only in the Gospels. In construction connect with διὸ Hebrews 3:7; therefore beware.

Lest there be (μήποτε ἔσται)

The indicative with μὴ lest shows that with the fear that the event may occur, there is blended a suspicion that it will occur.

In any of you (ἔν τινι ὑμῶν)

They are appealed to individually.

An evil head of unbelief (καρδία πονηρὰ ἀπιστίας)

The whole phrase N.T.o. Neither do the combinations evil heart or heart of unbelief occur elsewhere. In lxx, among nearly a thousand instances of καρδία heart, καρδία πονηρὰ evil heart appears only five times, and in three of the five in apocryphal books. See Sir. 9:1; Bar. 1:22; 2:8. In lxx proper, Jeremiah 16:12; Jeremiah 18:12. Ἀπιστίας of unbelief, specifies that in which the more general πονηρὰ evil consists. An evil heart is an unbelieving heart.

In departing from the living God (ἐν τῷ ἀποστῆναι ἀπὸ θεοῦ ζῶντος)

The characteristic of unbelief. Faith is personal union with God. Unbelief separates from God. The phrase living God is common to both Testaments. For the bearing of the words upon the question of the Gentile destination of the Epistle, see Introduction.