What does "nothing good dwells in me" mean (Romans 7:18)?

At least three things. First that he still has the old nature (sin). Then that nothing good dwells in him personally. And finally that he cannot deliver himself but needs someone else to deliver him.

(V. 18). Secondly, in this struggle to do right and overcome sin by legal efforts, another important truth is learnt. I discover the incorrigible evil of the flesh. As the Apostle says, "I know that in me (that is in my flesh) dwells no good thing". He does not say, "I do no good thing", but "in me … dwells no good thing". It is here a question of what I am, not of what I do. As a matter of fact the flesh can do many things that are morally right. Doubtless in the case supposed, the life was blameless. The failure was lust, and that is inward.

"In the flesh" is a term used in Scripture to set forth our fallen condition, governed by the old nature, as connected with Adam. Adam innocent was in the flesh, but without sin. The Lord Jesus too, was in the flesh, but without sin. By the fall the flesh, or nature of man, came under the dominion of sin, and so flesh became sinful flesh (Rom. 8:3). In this struggle to do right we discover that, in spite of all our efforts the flesh does not change. Lust again and again arises in the heart, showing that the old nature is there, and that it is incorrigible. We discover that not only there is a great deal of evil in the flesh, but that, in the flesh there is no good thing. We are brought to the point when we abhor ourselves.

Yet this only shows me more awfully than ever the utter badness of the flesh. All that I did before I was awakened was of course only sin; but it is a hundredfold worse to find that even when I want to perform that which is good, the flesh is incapable of it. In me, that is in my flesh, there dwelleth no good thing. I see good things which I want to do, but I don't do them; other things which I want to avoid because they are evil, I do (vv. 16-19).

First, the true character of the flesh (i.e., the old evil nature still within us), hopelessly bad. "I know that in me (that is, in my flesh) dwells no good thing" (Rom. 7:18). If "no good thing," then not even a good desire is to be found there. Yet how long it takes most of us to abandon all expectation of good or even improvement from within.

Second, the terrible power of the flesh. Such power that even the fact of being born again, and therefore possessing a new nature, does not of itself enable us to overcome. We find a man saying, "The good that I would I do not; but the evil which I would not, that I do" (Rom. 7:19). He desired the good, proving the existence of the new nature within him; yet such was the power of the old that it overpowered the new, bringing him into captivity (Rom. 7:23), and making him a thoroughly wretched man (Rom. 7:24).

The apostle Paul puts the same truth in different words when he says; "I know that in me (that is, in my flesh) dwells no good thing" (Rom. 7:18) - not even one spark of good.

He learns by experience the true character of that old nature. If it be a question of "me," that is, "the flesh" (here you see, it is the old "me" that he has to repudiate) in that no good is found, as verse 18 tells us. Good simply is not there. So it is useless searching for it. Have some of us spent weary months, or even years, looking for good in a place where it is non-existent?

So he says, “For I know that in me (that is, in my flesh) dwells no good thing” (v. 18). Here the writer identifies himself for the moment with the old I—the flesh—and by bitter experience learns its irremedial and unimprovable nature. Here is a great advance—he will cease to cultivate the flesh or expect any good from it.

It is impossible for a believer to know himself aright, or to account for what he must know passes within him, unless he is conscious of having these two natures; one of which cannot sin, because it is born of God; while the other can only sin, if allowed to break out, because it is contrary to God. Hence a soul taught of God is admonished to "sin not." He is also made to know that in him, that is, in his flesh, dwells no good thing. The believer cannot truthfully say, "In me dwells no good;" for he has a new nature divinely created, and the Holy Ghost also dwells in him; but he can say that "in me, that is, in my flesh, no good is."

But though the believer is not in the flesh, he sorrowfully finds that the flesh is in him. He learns through humbling experiences to say, "In me, that is in my flesh, dwelleth no good thing." He does not say, "In me dwells no good," because he has a new life, and the Holy Ghost in him; but he says, "In me, (that is in my flesh,) dwelleth no good thing;" for, though delivered from the Adam standing, he still has the Adam nature — the flesh, with its passions and lusts — that evil principle which is ready to serve the law of sin. He has, in fact, two natures: the old nature, "that which is born of the flesh," which "is flesh;" and the new life, or new nature, "that which is born of the Spirit," which "is spirit." The new nature which is born of the Spirit is strengthened by the Holy Ghost which indwells us; so that, while the flesh lusts against the Spirit, the Spirit is against the flesh in such antagonistic power, that we cannot do the things which we otherwise would. The delivered soul knows that he is the subject of the actings of these two opposing natures, and his conclusion is, "So then, with the mind I myself serve the law of God; but with the flesh the law of sin." (Rom. 7:25.)

We must remark here, that the subject treated of is not the fact of the conflict between the two natures, but the effect of the law, supposing the will to be renewed, and the law to have obtained the suffrage of the conscience and to be the object of the heart's affections — a heart which recognises the spirituality of the law. This is neither the knowledge of grace, nor of the Saviour Christ, nor of the Spirit. The chief point here is not condemnation (although the law does indeed leave the soul under judgment), but the entire want of strength to fulfil it, that it may not condemn us. The law is spiritual; but I, as man, am carnal, the slave of sin, whatever the judgment of my inward man may be: for I allow not that which I do. That which I would I do not; and that which I hate I practise. Thus loving and thus hating, I consent to the law that it is good. It is not that I do the evil as to moral intent of the will, for I would not the evil which I do; on the contrary I hate it. It is the sin then that dwells in me, for in fact in me (that is, in my flesh — the whole natural man as he is) there exists no good, for even where there is the will, I do not find the way to perform any good. Power is totally wanting.