Years ago when I read my daughter’s English paper, I was intrigued by her quote from Robert Louis Stevenson’s novel Dr. Jekyll and Mr. Hyde. Dr Jekyll had surmised, “If each [good force and evil force]. . . could be housed in separate identities, life would be relieved of all that was unbearable; the unjust might go his way, delivered from the separate aspirations and remorse of his more upright twin; and the just could walk steadfastly and securely on his upward path.”  She went on to describe how Dr. Jekyll “was intrigued by the mysteries of human life and character; after years of study he discovered a formula for separating the two parts of man. He carried out this experiment on himself (against his better judgment) and created Mr. Hyde–a wholly evil person.”
How often have we felt burdened and frustrated in our inward struggle against sin? What is the nature of this inner conflict in the life of the believer in Christ? How can we enjoy freedom from the power of sin and enjoy rest from such inner turmoil? Romans chapter 7 often refers to “the flesh” in the description ethical conflict. What does the Bible mean by “flesh”? This carnality is identified in Galatians 5:17: “For the flesh lusts against the (Holy) Spirit, and the Spirit against the flesh; and these are contrary to one another, so that you do not do the things that you wish.”
Sometimes we summarize our three spiritual enemies as
- the world (as the fallen system of humanity opposed to God–1 John 2:15-17),
- the flesh (our internal foe–Rom. 7:18), and
- the devil (Satan–1 Pet. 5:8).
Of these three, the flesh seems the most illusive and difficult to accurately identify.
So how can we define “flesh” when it is used in an ethical sense? It has been observed that you can take the “h” off of “flesh” and spell it backwards and you have “self”–the self used as a carnal spiritual condition.  Charles Solomon notes, “The believer, though he is no longer ‘in the flesh,’ may yet walk ‘after the flesh.’ The flesh is no longer a permanent “position” for the believer, but it is an all too frequent “condition” [Rom. 8:4-9] … Entering daily into freedom from the flesh may be hindered by carryovers from the past life in the soul. The mind has some thought patterns that were ingrained in the brain. There may also be some emotional damage sustained in childhood or later. The problems of the soul (mind, will, and emotions) must be worked through in the power of the Holy Spirit to achieve the full freedom belonging to every believer.” 
Misconceptions about the Flesh
We should clarify that the physical body is not our enemy. Genesis records that Adam and Eve were made with physical bodies in innocence “and God saw that it was good” (Gen. 1:31). Jesus received a human body at His incarnation and remained sinless. Unlike those who try to afflict their bodies to reduce the influence of sin, we should respect this earthly vessel that God has given as to live in and use it as “an instrument of righteousness” (Rom. 6:13; see 1 Cor. 6:19). Neither afflicting your body or trying to isolate your body has any lasting value in overcoming the power of sin (Col. 2:20-23).
Another misconception is that the believer is the victim of inner dualism–two opposing forces of good and evil which have an equal claim on his mind, character, and choices. I was originally taught that my new nature as a Christian was like a white dog and that my old, sinful nature was like a black dog; these were in constant tension. The remedy for this miserable condition was said to be to “feed the white dog.” –‘No wonder I felt like an old bone! (Now it is true that feeding your soul with prayer and the Word of God will influence you for godliness in your fight against sin, yet a closer examination of “the flesh” will indicate some good news about your birthright to live in freedom from the power of sin.)  Dualism in philosophy is the idea that good and evil are parallel forces in conflict in the world. This idea was popularized in the the Star Wars movies– “May the force be with you!”
Notice how this differs from the Christian worldview: although good and evil coexist in the world, they are not equal forces! God is good, sovereign, all-powerful, all-knowing, and unchanging. Recall the book of Job: Satan could do nothing beyond God’s permissive will. Satan was defeated at Calvary through Christ’s work on the Cross (Col 2:14); his doom is sure (Rev. 20:1-3).
Similarly, as a true believer in Christ, this same sovereign God indwells you by His Spirit. Romans 6:5-7 affirms that you have been identified with Christ.
“For if we have been united together in the likeness of His death, certainly we also shall be in the likeness of His resurrection, knowing this, that our old man was crucified with Him, that the body of sin might be done away with, that we should no longer be slaves of sin. For he who has died has been freed from sin.”
Therefore God’s Word does not teach dualism in the universe or in the believer’s nature. Instead of seeing yourself with a co-equal good nature and bad nature (half light and half dark), recognize that your essential nature is holy: “…put on the new man which was created according to God, in true righteousness and holiness” (Eph. 4:24). That is why God’s Word says you have been sanctified (Heb. 10:10) and therefore a “saint” (1 Cor. 1:2). This does not teach the eradication of sin as a negative influence in the Christian life, nor does it indicate the possibility of sinless perfection (James 3:2). We still have the flesh to contend with, but in Christ we have freedom from sin’s authority, we have the power of God’s Spirit, and we have the freedom to live righteously through grace!
Walking in the Spirit
Our strategy for victory over the flesh is a positive one: “I say then: Walk in the Spirit, and you shall not fulfill the lust of the flesh” (Gal. 5:16).
Bill Gillham described the implications of understanding these principles:
“Just because a Christian doesn’t have a sinful nature [in his spirit] doesn’t mean that we don’t struggle in our war against sin … Just as you can pick apples without having an apple-picking nature and eat pork without having a pork-eating nature, you can sin without having a sinful nature. ‘Nature’ is defined as ‘a fundamental characteristic.’ Sinners love sin. Saints hate it. Sinners plan ahead for more innovative ways to sin. Saints attend seminars to learn how to overcome it. Our fundamental characteristic is to avoid sinning.”  This is confirmed in 1 John 2:29, “If you know that He is righteous, you know that everyone who practices righteousness is born of Him” (see also 1 John 3:7-9;4:7;5:4).
So your “Mr. Hyde” was nailed to the Cross with Christ! The “old man” is out of the picture; you have a “new man”–a spirit that is alive unto God. Paul admonished, “… put off all these: anger, wrath, malice, blasphemy, filthy language out of your mouth. Do not lie to one another, since you have put off the old man with his deeds, and have put on the new man who is renewed in knowledge according to the image of Him who created him” (Col. 3:8-10). Notice that the “old man” as put off (past tense). This occurred when you were saved and spiritually united with Christ (1 Cor. 6:17). This union identified you with Christ’s death, burial, resurrection, and ascension! (Eph. 2:4-6).
In Alive for the First Time, David Needham emphasizes the value of clearly discerning our essential spiritual nature in Christ:
[Many believe that] whenever you are feeling sinful desires, you are actually encountering your fundamental nature–a sinner. In those hot, pressured times, you either follow through with those desires and do what you want or by God’s strength resist them and end up doing what you ought … Yet whether or not you obey the ‘oughts’, you still must reckon with the true nature of the kind of person you assume yourself to be–at heart, a sinful person. Whether or not we realize it, the desire of our inmost self is the same as Paul’s–‘for me to live is Christ!’ [Phil. 1:21] It is correct to speak of Christian self-denial within the limits of a sense of selfishness or self-centeredness, both of which are enemies of dependence [on God] …
How very important it is for Christians to be taught quickly that when they were saved, not only were they justified, but God also performed those interior miracles that changed the focus of their selfhood from flesh to spirit. Their deepest level of self, their truest self, never desires to sin [1 John 3:9]. That ‘self’ is always in perfect agreement with the ‘oughts’ of God’s moral law.” 
So, in Christ, we are free to chose to cooperate with God’s Holy Spirit and produce good fruit! When we do so, we act consistently with our essential nature; we walk in harmony with our true identity in Christ! God bless you, “Doctor”!
 Robert Louis Stevenson, Dr. Jeckyll and Mr. Hyde, p.105.
 The word “flesh” is a translation of the Greek word “sarx” which occurs 130 times in the New Testament. Sometimes it speaks of the physical body, or the material aspect of living things (Phil 1:22). When it is used in an ethical sense, however, it has many implications for our inward fight against sin. For example, 1 Peter 2:11 [used as an adjective-“sarkikos”] warns us: “Beloved, I beg you as sojourners and pilgrims, abstain from FLESHLY lusts which war against the soul. Cf. 2 Pet 2:18; 1 John 2:16.
 Charles Solomon, Gems and Jargon (Cross Life Expressions) p.10,11.
 Note: the term “sinful nature” is commonly used to describe the sin principle in the believer but can be misleading. The NIV translation of “flesh” as “sinful nature” in Rom 7:18 and elsewhere is too vague. A more literal translation as “flesh” (like NKJV or NASB) is needed for a precise understanding of this topic.
 Bill Gillham, What God Wishes Christians Knew About Christianity (Harvest House) p.102,103.
 David Needham, Alive for the Fist Time (Multnomah, 1995), p. 157-58. Cf. L. Berkhof on regeneration–“that act of God by which the principle of new life is planted in man, and the governing disposition of his heart is made holy.” (Systematic Theology, p.469.)
3rd edition. Copyright 1999 by John Woodward. Permission is granted to reprint for noncommercial use if credit is given to the author and GraceNotebook.com. Biblical quotations are from The Holy Bible, New King James Version (copyright by Thomas Nelson).