Read in a simplistic fashion, Paul’s pitting of flesh against spirit might seem to be on the order of a gnostic denigration of the physical body and the presumption that one must shed what is corporeal so as to embrace what is spiritual. It might be presumed that flesh, for Paul, is simply the body and one in the physical body is doomed to sin and corruption. The human problem, in this understanding, is being finite, physical, and made of flesh, and the resolution of this problem is to shed the fleshly body and be raised as an incorporeal spirit. In other words, Paul might be read as embracing a form of the belief that spirit and flesh are timeless principles pitted against one another (part of the cosmos) from the beginning. Louis Martyn’s point is that Paul is a dualist but not a dualist of this sort: “Since the Spirit is the Spirit of Christ (Gal. 4:6), it is obvious that the Spirit and the Flesh – as opponents – are a pair of opposites born not of God’s creative act, but of this new-creative act in the sending of his Son and the Spirit of the Son.” This is an eschatological dualism in which two ages overlap, “the present evil age” and the age commenced, not from the beginning of time, but from the apocalyptic moment of Christ’s breaking in. It is not only the Spirit but the flesh that is redefined by this moment. In fact, of the two terms it may be that “flesh” is the most misunderstood and misconstrued.
It is difficult to say anything definitive about the general usage of flesh in the Bible, as context fills in, whether the reference is to the total personality, to the emotions, or to the weak or corruptible part of man. In the Hebrew scriptures flesh appears sometimes as neutral and refers to the collective and individual creaturely existence or relationship. Though it is in creatureliness that sin takes hold, it is noteworthy that in one of the most authoritative of sources the conclusion is, “nowhere is it even probable that the flesh is in conflict with the spirit.” The flesh is that place where the battle between the Holy Spirit and the spirit of iniquity takes place but the flesh or the body is not itself the problem. In other words, the Hebrew scriptures are not picturing a cosmic conflict between flesh and spirit or between the corporeal and incorporeal. The body is not the prison of the soul, and the flesh need not keep man from true knowledge and experience of God. In the Midrash, Psalm 16:9 (“My flesh will dwell securely”) serves to show David as an example of one over whom the corrupting tendency of the flesh has no power. 
This conclusion carries over to the New Testament, where the flesh may be neutral, or may refer to a weakness or physical sickness, or it may be specifically designated as “sinful flesh.” In Mathew 16:17, “flesh and blood” denote a limitation, not in terms of mortality but as a medium by which to apprehend God. That is, even Jesus in the flesh may not be recognized due to fleshly intellectual, religious, and mystical limitations. 
Though the New Testament does not depict an anthropological or cosmic dualism, the peculiar role of the false teachers and the need to combat their focus on the flesh gives rise to what might be mistaken for this sort of dualism. It may be in both Galatians and Romans that Paul is mistakenly perceived as presenting a cosmic/anthropological dualism.
Flesh is depicted in Galatians as a force superior to man and might be numbered among the principalities and powers, and yet this same power is not alien to humans but belongs to them and arises from them. As the TDNT makes clear, Paul’s view is not that of the Gnostics that presumes “the divine core of man has been tragically overpowered by the sinister forces which seduce the senses” – this “is not Paul’s answer.” Paul does not pose flesh, per se, over and against the spirit as the flesh may simply denote the realm of marriage, of blood relations, or of human interaction (e.g., Col. 2:1,5). It can denote the muscular part of the body, or where one might experience disease or physiological weakness (2 Cor. 12:7; Gal. 4:13).
Too much devotion or trust in the flesh lends the flesh a power which it does not possess intrinsically. The sinful life is, by definition, oriented to the flesh or serves the flesh and this results in fleshly thinking, but being in the flesh or body is not inevitably sinful (Rom. 8:8-9). Christ specifically defeats the orientation to the flesh in the flesh and makes it possible for his followers to rid themselves of this orientation, not by getting rid of the body or flesh but by being oriented to the Spirit. Paul can say the believer no longer lives in the flesh, (Rom. 7:5; 8:8f.) not because he has abandoned the body but because the sinful orientation which he marks, by the shorthand of flesh, no longer controls. He describes the believer as crucifying the flesh with its passions and desires (Gal. 5:24). This is not a literal crucifixion and the flesh that dies is not the literal corporeal body, but the principle of sin attached to the orientation to the flesh. “Paul certainly does not mean that by ascetic or mystical practices man can escape his corporeality.” The believer always lives physically (ἐν σαρκί): “For though we walk in the flesh, we do not war according to the flesh, for the weapons of our warfare are not of the flesh, but divinely powerful for the destruction of fortresses” (2 Co 10:3–4). Paul says, “I now live in the flesh” but this living is now marked not by faith in the flesh but “by faith in the Son of God” (Gal. 2:20).
The false teachers of Galatia are deploying the term flesh in a fashion that may account for the peculiar usage demonstrated in Galatians. Martyn suggests that the Galatians, prior to the arrival of the false teachers, will not have received any peculiar Jewish or Christian teaching regarding the flesh, as Paul seems not to have mentioned it in his initial evangelistic campaign or his earlier writing (e.g., there is no similar warning in I Thess. 4:1-8). The false teachers may have drawn a connection between “the impulsive Desire of the Flesh” (ἐπιθυμίαν σαρκὸς) and their suggested resolution of circumcision. Abraham, in their estimate, would have defeated the desire of the flesh by keeping the law, beginning with circumcision. So, Paul’s juxtaposition of flesh against Spirit, specifically refers to the foreskin of the penis. Their reliance on the law is literally reliance on this piece of flesh.
As a result, Paul, in Galatians, has developed a unique designation for the flesh in which the “power of the flesh” stands over and against the “power of the promise” of God. The power of the flesh is intermixed with a trust in the law, which reduces in Paul’s argument to the same thing. The difference for Abraham between the “power of the flesh” and the “power of the promise” pertains primarily to the object of faith (4:21-31). In both instances the reference is to procreation and birth, but trust in the power of the flesh (the birth of Ishmael) is posed against the power that produced the birth of Isaac. In both kata sarka and kata pneuma the meaning of kata is “as a result of the power of.” The point is not that one is less bodily, less sexual, less fleshly. Both powers produce children in the same embodied manner and both directly reference the act of Abraham, but in one instance Abraham trusted the flesh and in the other instance he trusted God.
The false teachers, according to Paul, are repeating the mistake of Abraham (in conceiving Ishmael) in that they are trusting in the power of the flesh in their insistence on circumcision. This is on the order of trusting in the letter of the law, and thus missing the Spirit (2 Cor. 3:6). The problem is not that the law is conveyed in letters or that the power of the flesh uses the flesh, but it is the exclusive trust in the letter of the law or the power of the flesh. “Flesh versus spirit” might be a shorthand way of depicting this conflict, but this has nothing to do with an anthropological or cosmic antagonism between body and spirit. In both instances the same body and the same mode of conception are deployed, but the dynamic of the fleshly specifically entails an abandonment of trust in the power of God, and belief in the promise trusts God in this same circumstance.
The same dynamic is at work in Romans 7, which also may reflect a Hellenistic influence, but Paul is depicting the experience of fallen man and not every man. His is precisely not the Greek notion that νοῦς (mind, reason, understanding) can control the flesh. The impotence of the mind, its passive apprehension, is itself part of the agonistic dynamic Paul is describing. It is not a matter of the law of the mind gaining control of the law of the flesh, as both are part of the dynamic of the law of sin and death. It is not the body against the spirit that is causing the problem; in fact Paul’s pitting of his mind against the body seems to be part of the problem. He sees two laws at work: “I see a different law in the members of my body, waging war against the law of my mind and making me a prisoner of the law of sin which is in my members” (Rom. 7.23). The point is not that one of these laws is right and the other is wrong; the point is there is a war being waged in which the individual is the victim. As John Bertone notes, Paul’s object here is not to demarcate one form of law from the other: “The point is that this system represented something that simply did not produce life.”
Paul may be thinking of a Pharisaical drive to achieve righteousness through the law as the struggle of sin he is describing. Establishing one’s own righteousness is on the same order as trusting in the power of the flesh. The problem in both Romans 7 and Galatians is that certain individuals misperceive the function of the law, imagining that it produces life. The command (Rom. 7:11) which promised life did not point to itself (as the source of life) but to God. The perception of promise of life in the law is skewed by sin so as to remove the necessity of God: “this commandment, which was to result in life, proved to result in death for me; for sin, taking an opportunity through the commandment, deceived me and through it killed me” (Rom. 7:10-11). The correct nuance is to understand that the law keeps one in a life-giving relationship with God, but it is this relationship to God (and not with the law) that is the true source of life.
Just as the law was aimed at keeping one in relationship with God, this positive understanding can be carried over to the meaning of flesh. Where flesh “is understood in a full theological sense . . . it denotes the being of man which is determined, not by his physical substance, but by his relation to God.”
The problem with the law, the problem with the flesh, and the problem with “this present evil age” reduce to the singular problem that the “elements of the cosmos” (στοιχεῖα τοῦ κόσμου) have been made absolute and have not been understood in relationship to God. Whatever Paul might mean by these elements, it seems that the law and the flesh are counted among those things which held all people captive (Gal. 4:3). The law, the flesh, or simply the material order of creation, none of which are intrinsically sinful, enslave those who entrust themselves completely to this order. This is shown in the apocalyptic appearing of Christ which entails a “new creation” (Gal. 6:15). The old cosmic order is broken open and is being brought to an end as the new creation commences (which as Paul explains in his receiving of the Gospel is not dependent upon flesh and blood (1:16)).
“But may it never be that I would boast, except in the cross of our Lord Jesus Christ, through which the world has been crucified to me, and I to the world. For neither is circumcision anything, nor uncircumcision, but a new creation” (Gal. 6:14-15).
 J. Louis Martyn, Galatians: A New Translation with Introduction and Commentary (Yale University Press, 1997), 100.
 Schweizer, E., & Baumgärtel, F. (1964–). σάρξ, σαρκικός, σάρκινος. G. Kittel, G. W. Bromiley, & G. Friedrich (Eds.), Theological dictionary of the New Testament (electronic ed., Vol. 7, p. 114). Grand Rapids, MI: Eerdmans.
 Ibid, 115.
 Ibid, 124.
 Ibid, 133-134.
 Ibid, 134
 Martyn, 293-294.
 Martyn, 434-435.
 John A. Bertone, “The Law of the Spirit”: Experience of the Spirit and Displacement of the Law in Romans 8:1-16, (New York: Peter Lang Publishing, 2005) 180..
 Ibid, TDNT, 134.