Read Rom. 7-8.
Many Christians are often conscious of many conflicting desires and emotions. In thought, word, and action, they find the strangest possible jumble of good and evil which is very perplexing to them.
This is cleared up when we realize that the believer has two distinct natures, the new and the old. The new nature is the source of every right desire whereas the old is the source of only evil. A hen wouldn't know what to do if made to mother a mixed brood of chicks and ducklings because their natures and consequently their actions are very different. Many Christians are like that hen.
The Lord Jesus told Nicodemus that he had to be born again - "born of water and of Spirit." The Lord then added, "That which is born of the flesh is flesh and that which is born of the Spirit is spirit" (Jn. 3:5-6). The two words flesh and spirit plainly indicate the existence of two natures, each characterized by its source. The first is called flesh because it springs from the flesh. The other is called spirit because it springs from the Holy Spirit.
We can thus speak of the flesh as the old nature because we have it as the result of our birth into Adam's race. Spirit is thus the new nature which we get in new birth as born of the Holy Spirit. However, don't get spirit, our new nature, mixed up with God the Holy Spirit. The new nature, spirit, is the direct result of the Holy Spirit's wonder-working power so, although they are closely connected, the two uses of the word "spirit" are distinct.
When you were born again, the Holy Spirit implanted in you this new nature and one of the first results was a fight between it and the old nature. Both natures strive for mastery, each pulling in opposite directions. Until the secret of deliverance from the power of the flesh is learned, the painful jumble of right and wrong will continue. That painful experience is described for us in Rom. 7. Read it, especially v. 14 to 8:4. Do you see many of your own experiences there?
Paul reaches one very important conclusion in Rom. 7:18. He says "I know that in me (that is, in my flesh) dwells no good thing." The flesh is completely bad. God allows us to wade through the mud of bitter experience so that we may thoroughly learn this vital lesson. The Lord Himself said, "The flesh profits nothing" (Jn. 6:63). Paul again states the same thing in Rom. 8:8, "Those who are in the flesh cannot please God." Only evil can possibly come from the flesh, our old nature.
Uncared for and untrained flesh becomes heathen and savage, whereas educated and refined flesh becomes restrained, civilized and even religious but it is still flesh. That which is born of flesh is flesh, no matter what you do with it. Absolutely no good thing dwells in even high class flesh. What can be done with a nature in which sin dwells and works? What has God done with it? What is His remedy?
God answers in Rom. 8:3, "For what the law could not do in that it was weak through the flesh, God, sending His own Son in the likeness of sinful flesh and for sin, condemned sin in the flesh." The law strongly censured the flesh but it could neither curb nor even control it so that we might be delivered from its power. But in the cross of Christ, God has judicially dealt with it. He "condemned sin in the flesh" - condemned it in the very root of its nature.
Rom. 8:4 gives the practical result of this. We have the Holy Spirit to be the power of the new nature so as we walk in the Spirit, we fulfill all the righteous requirements of the law although we are no longer under it as our rule of life.
Even though God has condemned our old nature in the cross of Christ, what can we do with it? Well, we can thankfully accept what God has done and treat our old nature as a condemned thing! We can have absolutely "no confidence in the flesh" (Phil. 3:3).
Do we really understand the true character of the flesh, that in it dwells no good thing and that God has condemned it? Have we reached the point where we have no confidence in it, even in its best forms? This point is not easily reached. Many painful experiences and heart-breaking failures are often passed through as again and again the flesh comes in to damage or wreck our most pious and prayerful resolutions. But once that point is reached, the major battle is just about over.
The shattering of our confidence in the flesh is largely the shattering of the flesh's power over us. This occurs when we look away from ourselves and our most earnest efforts and find a Deliverer in the Lord Jesus Christ Who has taken possession of us by the Holy Spirit. The Holy Spirit is the power: He both checkmates the activity of the old nature (Gal. 5:16) and energizes, expands, and controls the new nature (Rom. 8:2, 4-5, 10) if we allow Him to do so.
It is very important to realize that the new nature has not power in itself. Rom. 7 shows us that. The new nature gives us good and beautiful thoughts and desires but is powerless to fulfill them. The power comes in complete practical submission to Christ and to the Holy Spirit! This "walking in the Spirit" largely results from our coming into real agreement with God's condemnation of the old nature in the cross of Christ.
All people, even those who are naturally good natured and even religious, need this new nature. In fact, the man to whom the Lord Jesus said "you must be born again" (Jn. 3:7) was about as good a man as could be found. Morally, socially, and religiously, everything was in his favor yet the Lord said that he needed new birth. Good natured and religious flesh is still only flesh and it will not satisfy or please God in any way!
Thus we see that, as for as God is concerned, no one by natural birth has even a spark of good in him, For instance, in Rom. 3:9-19, we have a complete account of mankind in his moral features. In vv. 10-12 we have sweeping, all-inclusive statements. Then we have the terrible details of some of these features in vv. 13-18. In all these words from the God Who can not lie, there is not one word about even a spark of good in mankind because that spark is not there! Scripture is even more positive. Gen. 6:5 tells us that "God saw that wickedness of man was great in the earth and that every imagination of the thoughts of his heart was only evil continually." Paul had learned this truth. In Rom. 7:18, he said "I know that in me (that is, in my flesh) dwells no good thing" - not even one spark of good!
Remember also that every believer has both the old and the new nature. The old nature is not eradicated at new birth and it is not changed by new birth into the new nature. Both natures are in every believer. The process of "grafting" illustrates this. A choice, good and cultivated apple-shoot can be grafted into a wild, useless tree and the tree then can yield good fruit and is in fact then known by the apple-variety that was grafted in. The same is true with us. Both natures are there but God only recognizes the new one so we are "not in flesh but in the (Holy) Spirit" (Rom. 8:9).
Further remember that no amount of human effort will avail against out old nature. To have victory over it, we have to think of it and treat it as God does. God entitles you to disown the old nature because the new nature is your true self once you are saved just as the cultivated apple is the recognized nature of the tree as soon as the graft is effective. Your treatment of the old nature is simple. In grafting, the gardener carefully watches his tree if he wants good fruit from it. If the old wild stock seeks to assert itself by throwing up suckers from its roots, the gardener ruthlessly cuts them down as soon as they appear. Likewise, we must quickly and ruthlessly bring the cross of Christ to bear like a sharp knife on our old nature and all of its sinful desires.
Col. 3:5 tells us to "mortify (make dead) your members which are upon earth" - cut down the wild suckers. These "suckers" are detailed for us in vv. 5, 8, and 9. We are to put them to death in detail. This takes spiritual energy, courage, and purpose-of-heart which you can only have when you willingly look only to the Lord Jesus and place yourself fully in the hands of the Holy Spirit. "If you through the (Holy) Spirit do mortify the deeds of the body, you shall live" (Rom. 8:13). (Of course, this does not speak of physical damage to your physical body but through the Holy Spirit's help, you consider you body as dead to the deeds of the old nature. We see this in Paul's statement in 1 Cor. 9:27, Ed.).
Thus the Holy Spirit's power is obtained only when we "yield ourselves unto God as those who are alive from the dead, and our member as instruments of the righteousness unto God" (Rom. 6:13). Rom. 6:19 says to "yield your members servants to righteousness unto holiness." See also Rom. 6:22. The thought that such power is obtained by some act of our own will (other than to yield that will to God) is a last desperate attempt to somehow obtain a little bit of credit for the flesh instead of totally condemning it all and giving all the glory for victory to God.
The new nature never reaches such perfect growth on earth that a believer will never again sin. An example of this fact is given in 2 Cor. 12:1-10. Paul had been especially blessed by being caught up into the third heaven, into the presence of God. He had seen and heard things that no human language could describe. Then Paul had to resume his ordinary life on earth. From then on, God gave him a "thorn in the flesh" - some infirmity - so that he wouldn't be exalted above measure i.e., think too highly of himself because he had been specially privileged. Paul's Christian living was very godly and advanced but all that was absolutely no insurance against the pride and self-glory which is inherent to the old nature. If Paul was not immune, neither are we.
In closing, let's see how we can distinguish between the desires which come from the old nature and from the new nature. There is no all-inclusive, easy rule. We must continually use the Word of God which is "living and powerful and sharper than any two-edged sword...and is a discerner of the thoughts and intents of the heart" (Heb. 4:12). Then the throne of grace is always available by prayer so that we may "find grace for seasonable help" (Heb. 4:16 R.V.). Thus Bible study and earnest, exercised prayer are absolutely necessary to enable us to untangle and distinguish the thoughts and desires which we find within us!
However, we can give one general rule. The new nature is always true to God and old nature is always true to self. All that has Christ as its object is of the new nature whereas all that has self as its object is of the old nature. Thus, many perplexing questions and problems would be solved by honestly asking, "What is the real (secret) motive which makes me want to do or not to do this or that? Is it for Christ-glorification or for self-gratification?"