“Abstain from fleshly lusts, which war against the soul.”
1 Peter 2:11
Temptation and Sin
Works, vol. 6, exc. ch. 6.
The Lust of the Flesh.
First, In general it is said to lust: Gal. 5:17, “The flesh lusteth against the Spirit.” This word expresseth the general nature of that opposition which the law of sin maketh against God and the rule of his Spirit or grace in them that believe; and, therefore, the least degree of that opposition is expressed hereby. When it doth any thing, it lusteth; as, because burning is the general acting of fire, whatever it doth else, it doth also burn. When fire doth any thing it burns; and when the law of sin doth any thing it lusts.
Hence, all the actings of this law of sin are called “The lusts of the flesh:” Gal. 5:16, “Ye shall not fulfil the lust of the flesh;” Rom. 13:14, “Make no provision for the flesh, to fulfil the lusts thereof.” Nor are these lusts of the flesh those only whereby men act their sensuality in riot, drunkenness, uncleanness, and the like; but they comprehend all the actings of the law of sin whatever, in all the faculties and affections of the soul. Thus, Eph. 2:3, we have mention of the desires, or wills, or “lusts of the mind,” as well as of the “flesh.” The mind, the most spiritual part of the soul, hath its lusts, no less than the sensual appetite, which seems sometimes more properly to be called the “flesh.” And in the products of these lusts there are “defilements of the spirit” as well as of the “flesh,” 2 Cor. 7:1, — that is, of the mind and understanding, as well of the appetite and affections, and the body that attends their service. And in the blamelessness of all these consists our holiness: 1 Thess. 5:23, “The God of peace sanctify you wholly; and I pray God, your whole spirit, and soul, and body, be preserved blameless unto the coming of our Lord Jesus Christ.” Yea, by the “flesh” in this matter the whole old man, or the law of sin, is intended: John 3:6, “That which is born of the flesh is flesh,” — that is, it is all so, and nothing else; and whatever remains of the old nature in the new man is flesh still. And this flesh lusteth, — this law of sin doth so; which is the general bottom and foundation of all its opposition unto God. And this it doth two ways:—
The Flesh Lusts in Two Ways.
1. In its habitual propensity unto evil.
1. In a hidden, close propensity unto all evil. This lies in it habitually. Whilst a man is in the state of nature, fully under the power and dominion of this law of sin, it is said that “every figment of his heart is evil, and that continually,” Gen. 6:5. It can frame, fashion, produce, or act nothing but what is evil; because this habitual propensity unto evil that is in the law of sin is absolutely predominant in such a one. It is in the heart like poison that hath nothing to allay its venomous qualities, and so infects whatever it touches. And where the power and dominion of it is broken, yet in its own nature it hath still an habitual propensity unto that which is evil, wherein its lusting doth consist.
Inclination of the Heart vs. Inclination of the Law of Sin in the Heart.
But here we must distinguish between the habitual frame of the heart and the natural propensity or habitual inclination of the law of sin in the heart. The habitual inclination of the heart is denominated from the principle that bears chief or sovereign rule in it; and therefore in believers it is unto good, unto God, unto holiness, unto obedience. The heart is not habitually inclined unto evil by the remainders of indwelling sin; but this sin in the heart hath a constant, habitual propensity unto evil in itself or its own nature. This the apostle intends by its being present with us: “It is present with me;” that is, always and for its own end, which is to lust unto sin.
It is with indwelling sin as with a river. Whilst the springs and fountains of it are open, and waters are continually supplied unto its streams, set a dam before it, and it causeth it to rise and swell until it bear down all or overflow the banks about it. Let these waters be abated, dried up in some good measure in the springs of them, and the remainder may be coerced and restrained. But still, as long as there is any running water, it will constantly press upon what stands before it, according to its weight and strength, because it is its nature so to do; and if by any means it make a passage, it will proceed. So is it with indwelling sin; whilst the springs and fountains of it are open, in vain is it for men to set a dam before it by their convictions, resolutions, vows, and promises. They may check it for a while, but it will increase, rise high, and rage, at one time or another, until it bears down all those convictions and resolutions, or makes itself an under-ground passage by some secret lust, that shall give a full vent unto it. But now, suppose that the springs of it are much dried up by regenerating grace, the streams or actings of it abated by holiness, yet whilst any thing remains of it, it will be pressing constantly to have vent, to press forward into actual sin ; and this is its lusting.
Habitual propensity to evil is evident in two ways.
And this habitual propensity in it is discovered two ways:—
(1.) The unexpected flaring up of sin in the soul.
(1.) In its unexpected surprisals of the soul into foolish, sinful figments and imaginations, which it looked not for, nor was any occasion administered unto them. It is with indwelling sin as it is with the contrary principle of sanctifying grace. This gives the soul, if I may so say, many a blessed surprisal. It oftentimes ingenerates and brings forth a holy, spiritual frame in the heart and mind, when we have had no previous rational considerations to work them thereunto. And this manifests it to be an habitual principle prevailing in the mind: so Cant. 6:12, “Or ever I was aware, my soul made me as the chariots of Amminadib;” that is, free, willing, and ready for communion with Christ. לֹא יָדַעְתִּי; — “I knew not; it was done by the power of the Spirit of grace; so that I took no notice of it, as it were, until it was done.” The frequent actings of grace in this manner, exciting acts of faith, love, and complacency in God, are evidences of much strength and prevalency of it in the soul. And thus, also, is it with indwelling sin; ere the soul is aware, without any provocation or temptation, when it knows not, it is cast into a vain and foolish frame. Sin produceth its figments secretly in the heart, and prevents the mind’s consideration of what it is about. I mean hereby those “actus primo primi,” first acts of the soul; which are thus far involuntary, as that they have not the actual consent of the will unto them, but are voluntary as far as sin hath its residence in the will [c.f. WCF 6:5]. And these surprisals, if the soul be not awake to take speedy care for the prevention of their tendency, do oftentimes set all, as it were, on fire, and engage the mind and affections into actual sin: for as by grace we are oftentimes, ere we are aware, “made as the chariots of a willing people,” and are far engaged in heavenly-mindedness and communion with Christ, making speed in it as in a chariot; so by sin are we oftentimes, ere we are aware, carried into distempered affections, foolish imaginations, and pleasing delightfulness in things that are not good nor profitable. Hence is that caution of the apostle, Gal. 6:1, Ἐὰν προληφθῇ· — “If a man be surprised at unawares with a fault, or in a transgression.” I doubt not but the subtlety of Satan and the power of temptation are here taken into consideration by the apostle, which causeth him to express a man’s falling into sin by προληφθῇ, — “if he be surprised.” So this working of indwelling sin also hath its consideration in it, and that in the chiefest place, without which nothing else could surprise us; for without the help thereof, whatever comes from without, from Satan or the world, must admit of some parley in the mind before it be received, but it is from within, from ourselves, that we are surprised. Hereby are we disappointed and wrought over to do that which we would not, and hindered from the doing of that which we would.
Hence it is, that when the soul is oftentimes doing as it were quite another thing, engaged quite upon another design, sin starts that in the heart or imaginations of it that carries it away into that which is evil and sinful. Yea, to manifest its power, sometimes, when the soul is seriously engaged in the mortification of any sin, it will, by one means or other, lead it away into a dalliance with that very sin whose ruin it is seeking, and whose mortification it is engaged in! But as there is in this operation of the law of sin a special enticing or entangling, we shall speak unto it fully afterward. Now, these surprisals can be from nothing but an habitual propensity unto evil in the principle from whence they proceed; not an habitual inclination unto actual sin in the mind or heart, but an habitual propensity unto evil in the sin that is in the mind or heart. This prevents the soul with its figments. How much communion with God is hereby prevented, how many meditations are disturbed, how much the minds and consciences of men have been defiled by this acting of sin, some may have observed. I know no greater burden in the life of a believer than these involuntary surprisals of soul; involuntary, I say, as to the actual consent of the will, but not so in respect of that corruption which is in the will, and is the principle of them. And it is in respect unto these that the apostle makes his complaint, Rom. 7:25. 
(2.) The readiness to give in to temptation.
(2.) This habitual inclination manifests itself in its readiness and promptness, without dispute or altercation, to join and close with every temptation whereby it may possibly be excited. As we know it is in the nature of fire to burn, because it immediately lays hold on whatever is combustible, let any temptation whatever be proposed unto a man, the suitableness of whose matter unto his corruptions, or manner of its proposal, makes it a temptation; immediately he hath not only to do with the temptation as outwardly proposed, but also with his own heart about it. Without farther consideration or debate, the temptation hath got a friend in him. Not a moment’s space is given between the proposal and the necessity there is incumbent on the soul to look to its enemy within. And this also argues a constant, habitual propensity unto evil.
Outward vs. Inward Temptation.
Our Saviour said of the assaults and temptations of Satan, “The prince of this world cometh, and he hath no part in me,” John 14:30. He had more temptations, intensively and extensively, in number, quality, and fierceness, from Satan and the world, than ever had any of the sons of men; but yet in all of them he had to deal only with that which came from without. His holy heart had nothing like to them, suited to them, or ready to give them entertainment: “The prince of this world had nothing in him.” So it was with Adam. When a temptation befell him, he had only the outward proposal to look unto; all was well within until the outward temptation took place and prevailed. With us it is not so. In a city that is at unity in itself, compact and entire, without divisions and parties, if an enemy approach about it, the rulers and inhabitants have no thoughts at all but only how they may oppose the enemy without, and resist him in his approaches. But if the city be divided in itself, if there be factions and traitors within, the very first thing they do is to look to the enemies at home, the traitors within, to cut off the head of Sheba, if they will be safe. All was well with Adam within doors when Satan came, so that he had nothing to do but to look to his assaults and approaches. But now, on the access of any temptation, the soul is instantly to look in, where it shall find this traitor at work, closing with the baits of Satan, and stealing away the heart; and this it doth always, which evinceth an habitual inclination. Ps. 38:17, saith David, “I am ready to halt,” or for halting: כִּי־אֲנִי לְצֶלַע נָכוֹן; — “I am prepared and disposed unto hallucination, to the slipping of my foot into sin,” verse 16, as he expounds the meaning of that phrase, Ps. 78:2-3. There was from indwelling sin a continual disposition in him to be slipping, stumbling, halting, on every occasion or temptation. There is nothing so vain, foolish, ridiculous, fond, nothing so vile and abominable, nothing so atheistical or execrable, but, if it be proposed unto the soul in a way of temptation, there is that in this law of sin which is ready to answer it before it be decried by grace.
And this is the first thing in this lusting of the law of sin, — it consists in its habitual propensity unto evil, manifesting itself by the involuntary surprisals of the soul unto sin, and its readiness, without dispute or consideration, to join in all temptations whatever.
2. In its actual pursuit of evil and opposition to good.
2. Its lusting consists in its actual pressing after that which is evil, and actual opposition unto that which is good. The former instance showed its constant readiness to this work; this now treats of the work itself. It is not only ready, but for the most part always engaged.
“It lusteth,” saith the Holy Ghost. It doth so continually. It stirreth in the soul by one act or other constantly, almost as the spirits in the blood, or the blood in the veins. This the apostle calls its tempting: James 1:14, “Every man is tempted of his own lust.” Now, what is it to be tempted? It is to have that proposed to a man’s consideration which, if he close withal, it is evil, it is sin unto him. This is sin’s trade: Ἐπιθυμεῖ· — “It lusteth.” It is raising up in the heart, and proposing unto the mind and affections, that which is evil; trying, as it were, whether the soul will close with its suggestions, or how far it will carry them on, though it do not wholly prevail. Now, when such a temptation comes from without, it is unto the soul an indifferent thing, neither good nor evil, unless it be consented unto; but the very proposal from within, it being the soul’s own act, is its sin.
And this is the work of the law of sin, — it is restlessly and continually raising up and proposing innumerable various forms and appearances of evil, in this or that kind, indeed in every kind that the nature of man is capable to exercise corruption in. Something or other, in matter, or manner, or circumstance, inordinate, unspiritual, unanswerable unto the rule, it hatcheth and proposeth unto the soul. And this power of sin to beget figments and ideas of actual evil in the heart the apostle may have respect unto, 1 Thess. 5:22, Ἀπὸ παντὸς εἴδους πονηροῦ ἀπέχεσθε· — “Keep yourselves from every figment or idea of sin in the heart;” for the word there used doth not anywhere signify an outward form or appearance: neither is it the appearance of evil, but an evil idea or figment that is intended. And this lusting of sin is that which the prophet expresseth in wicked men, in whom the law of it is predominant: Isa. 57:20, “The wicked are like the troubled sea, when it cannot rest, whose waters cast up mire and dirt;” a similitude most lively, expressing the lustings of the law of sin, restlessly and continually bubbling up in the heart, with wicked, foolish, and filthy imaginations and desires.
This, then, is the first thing in the opposition that this enmity makes to God, — namely, in its general inclination, it “lusteth.”
 The terminology, “actual sin” does not mean that original sin is not really and truly sin, rather it is referring to sinful actions rather than the inclination toward sin (habitus). Westminster Confession of Faith 6:4-6 summarizes:
IV. From this original corruption, whereby we are utterly indisposed, disabled, and made opposite to all good,a and wholly inclined to all evil,b do proceed all actual transgressions.c
a. Rom 5:6; 7:18; 8:7; Col 1:21. • b. Gen 6:5; 8:21; Rom 3:10-12. • c. Mat 15:19; Eph 2:2-3; James 1:14-15.
V. This corruption of nature, during this life, doth remain in those that are regenerated;a and although it be through Christ pardoned and mortified, yet both itself and all the motions thereof are truly and properly sin.b
a. Prov 20:9; Ecc 7:20; Rom 7:14, 17-18, 23; James 3:2; 1 John 1:8, 10. • b. Rom 7:5, 7-8, 25; Gal 5:17.
VI. Every sin, both original and actual, being a transgression of the righteous law of God, and contrary thereunto,a doth, in its own nature, bring guilt upon the sinner,b whereby he is bound over to the wrath of Godc and curse of the law,d and so made subject to death,e with all miseries spiritual,f temporal,g and eternal.h
a. 1 John 3:4. • b. Rom 2:15; 3:9, 19. • c. Eph 2:3. • d. Gal 3:10. • e. Rom 6:23. • f. Eph 4:18. • g. Lam 3:39; Rom 8:20. • h. Mat 25:41; 2 Thes 1:9.
 William Perkins likewise explains:
“Lust is twofold: either without consent of will; as when unchaste desires come into the mind and heart, and are not entertained of the will, but be speedily checked so soon as they arise; and such lust is forbidden in the tenth commandment; or with consent of will, when a man is willing to entertain and cherish the thoughts that come into his mind, though he never puts them into practice; and these are forbidden in the seventh commandment.”
Exposition of Christ’s Sermon on the Mount (at Mat. 7:27), Works, vol. 1, p. 290.