In the third chapter of Indwelling Sin in Believers by John Owen, he moved on from describing how indwelling sin was a law to where it is located, what are its properties and how it operates.  First, Owen noted that everywhere in Scripture indwelling sin is said to have its “especial residence” in the heart. Citing Matthew 15:19, he listed how evil thoughts, murders, adulteries, fornications, thefts and other sinful actions proceed from the heart. There are many outward temptations that excite and stir up these evils, but they merely open the vessel and let out what was already laid up and stored there. “The root, rise, and spring of all these things is in the heart. Temptations and occasions put nothing into a man, but only draw out what was in him before.”

From the very beginning, God saw that every intention of the human heart was “only evil continually” (Genesis 6:5). In Luke 6:45, Jesus referred to the evil treasure of the heart, which Owen said was “the prevailing principle of moral actions” in humanity. Note how the beginning of the verse also points to “the good treasure of the heart,” referring to the grace received from our Savior. This good treasure will never be exhausted. The more we draw out of this treasure, the more it grows! And their indwelling sin decreases. However, the more we exert and manifest the fruit of our lusts, the more they are increased in us. “It feeds upon itself, swallows up its own poison, and grows thereby.”

The more men sin, the more are they inclined unto sin. It is from the deceitfulness of this law of sin, whereof we shall speak afterward at large, that men persuade themselves that by this or that particular sin they shall so satisfy their lusts as that they shall need to sin no more. Every sin increaseth the principle, and fortifieth the habit of sinning. It is an evil treasure that increaseth by doing evil. And where doth this treasure lie? It is in the heart; there it is laid up, there it is kept in safety. All the men in the world, all the angels in heaven, cannot dispossess a man of this treasure, it is so safely stored in the heart.

As an aside Owen commented how the heart in Scripture has various meanings. Sometimes it refers to the mind and understanding; sometimes to the will, sometimes the emotions (or affections); and sometimes to the whole soul. It typically refers to the whole soul and all its faculties, but not always. However all these faculties act together as one principle when doing good or evil.

This is the subject, the seat, the dwelling-place of this law of sin,—the heart; as it is the entire principle of moral operations, of doing good or evil, as out of it proceed good or evil. Here dwells our enemy; this is the fort, the citadel of this tyrant, where it maintains a rebellion against God all our days. Sometimes it hath more strength, and consequently more success; sometimes less of the one and of the other; but it is always in rebellion whilst we live.

The properties of the heart include that it is unsearchable, except by the Lord (Jeremiah 17:9-10). Can anyone know the perfect measure of their own light and darkness? “We fight with an enemy whose secret strength we cannot discover.” Often we think sin is quite ruined, but after awhile we find it was merely out of sight. It has places to hide in an unsearchable heart where we cannot enter. We might persuade ourselves that all is well, when sin is safely hidden in the hidden darkness of our mind, or the will’s indisposition, or the disorder and carnality of the emotions.

The best of our wisdom is but to watch its first appearances, to catch its first under-earth heavings and workings, and to set ourselves in opposition to them; for to follow it into the secret corners of the heart, that we cannot do.

Not only is the heart unsearchable, it is also deceitful. The deceit we see in the world around us is nothing in comparison to the deceit in our hearts towards ourselves. “Now, incomparable deceitfulness, added to unsearchableness, gives a great addition and increase of strength to the law of sin, upon the account of its seat and subject.” Owen wants us to be clear that he speaks here of the deceitfulness of the heart, and not of sin itself. And this deceitfulness of the heart has two advantages in harboring sin.

First, it abounds in contradictions, so there is not any constant rule by which it proceeds. “The frame of the heart is ready to contradict itself every moment.” Whenever you think you have everything under control, you quickly discover it is “quite otherwise.” So no one knows what to expect from it. This is because of sin working upon all the faculties of the heart. Sometimes the mind is subjected to God’s will, as are the emotions, and the will is ready for its duty. But if the emotions rebel or an obstinate will arises and prevails, everything is changed.

This, I say, makes the heart deceitful above all things: it agrees not at all in itself, is not constant to itself, hath no order that it is constant unto, is under no certain conduct that is stable; but, if I may so say, hath a rotation in itself, where ofttimes the feet lead and guide the whole.

Second, its deceit lies in the initial appearance of things. Sometimes our emotions are moved and “the whole heart appears in a fair frame; all promiseth to be well.” But in a little while, the whole frame is changed—the mind was not affected or turned; the emotions played their part at first, and then wandered off; and all the fair promises of the heart left with them. Add this deceitfulness to the previously mentioned unsearchableness, and we find that the difficulty of dealing with sin is exceedingly increased. Who can cope with a deceived and unsearchable heart? Particularly since it employs all its deceits in the service of sin.

All the disorder that is in the heart, all its false promises and fair appearances, promote the interest and advantages of sin. Hence God cautions the people to look to it, lest their own hearts should entice and deceive them.

Therefore it is not for nothing that the Lord says in Jeremiah 17:9 that “the heart is deceitful above all things and desperately sick.” So consider these things. First, never think that your work in contending against sin is at an end. It hides within the unsearchable places of our heart. So when we think we have thoroughly won, there is some reserve of sin remaining that we missed. Second, since our heart is changeable and deceitful, we should be perpetually watchful against it. Against an adversary that deals in deceit and treachery, only perpetual watchfulness will give you security. Third and finally, commit the whole matter to Him who can search and know your heart (Jeremiah 17:10). For there is no treacherous corner in your heart that He cannot search to its uttermost.

A digital copy of Owen’s work, Indwelling Sin in Believers, is available here.