One of the easiest subjects to misunderstand in Pauline theology is his flesh and spirit polarity. A common misconception is that by “flesh” Paul refers to the human lower nature, and by “spirit” he refers to the higher nature. This assumption seems to underlie the translation of sarx in the NIVs rendering of Paul’s letters. Though most standard English versions use the more literal translation of “flesh” (so KJV, RSV, ASV, NAB, NASB), the NIV opts for a dynamic equivalency and consistently renders it as “sinful nature” some twenty-four times, all but two of which are in the Pauline corpus. I must agree with Leander Keck when he says, “This is precisely what Paul does not mean!” To be sure, the Greek word sarx (= flesh) carries several nuances. At the simplest level, it refers to the fleshly material that covers the bones of a human or animal, and at times it can serve as a synonym for the body itself. At other times, the word clearly has a more metaphorical meaning and approximates the mortality of humans. Translators who attempt to find dynamic equivalencies for this word in Paul offer two renderings, one that emphasizes the earthly, mortal nature of humans, and the other that seeks to make human flesh the locus of sin.
There is no doubt that in Paul there is a connection between flesh and sin, but just what is that connection? Paul says, for instance, that in our former life “in the flesh” our sinful passions were aroused and expressed, bearing fruit toward death (Ro. 7:5). He offers a long litany of sins that he labels the “acts of the flesh” (Ga. 5:19). After coming to Christ, believers no longer live “according to the flesh” (Ro. 8:4) even though they live “in the flesh” (Ga. 2:20). Nevertheless, Paul’s letters fall short of saying that the flesh is the actual locus of sin. Rather, he says that the flesh is the arena of human weakness, and because it is weak, it becomes the tool of sin (Ro. 8:3; cf. 7:11). Sin is successful because of the flesh’s weakness. It is the field of force—the weak field of force--in which sin operates.
Paul’s understanding of the flesh derives from the Hebrew tradition, where humans are a unity, rather than the Greek tradition, where humans are a dichotomy. Sarx, which follows the Hebrew basar (= flesh, body), is Paul’s way of characterizing the human self in distinction from God (cf. Is. 31:3; 40:6-8; Je. 17:5, etc.). Human beings are flesh, that is, they are transitory, mortal and finite. The flesh, in itself, is morally neutral. Of his own susceptibility to illness, Paul can say that this was a “weakness of the flesh” (Ga. 4:13; cf. 2 Co. 12:7). Of the normal troubles that all married couples face, Paul can say that these are “afflictions of the flesh” (1 Co. 7:28). Paul can speak of his “kinsmen according to the flesh” with no moral overtone (Ro. 9:3). He can speak of other people as creatures of “flesh and blood” with no moral overtone (Ga. 1:16). He can even speak of Christ in his incarnation as descended from David “according to the flesh”, but one should hardly wish to read that Christ was descended from David “according to the sinful nature” (Ro. 1:3; 9:5). Hence, the flesh is the human self in all its powerlessness and limitation. In it, there is no power to do good (Ro. 7:18). In fleshly weakness, humans cannot please God (Ro. 8:8).