The references to life in the flesh remind us that there are standards of conduct which appeal to the natural man. He has desires which do not accord with the dictates of the Spirit of God. Indeed, part of the work of the Spirit is to show up every evil within man. "The more sanctified a man is, the more will he acknowledge the wretchedness of his own heart. This is the saving work of the Holy Spirit: this is the deepening conviction of sin without which no man shall be sanctified." Sometimes desire issues in crude lust, which, I suppose, is what most people in modern times associate with "the flesh." But there are "desires. . . of the mind" which may be linked to "desires of the flesh" (Eph. 2:3). . . The flesh . . . stands for that part of man's nature wherein his natural desires have free reign. "I know that in me," writes Paul, "that is, in my flesh, dwells no good thing" (Rom. 7:18). The flesh is the whole man, apart from Christ. Life "in the flesh," then may issue in a repulsive pandering to the more obvious forms of self-gratification. Or it may result, if the flesh is very "nice" flesh, in a refined, artistic or intellectual pursuit of one's aims and desires. It may even take a religious hue, though the religion will perforce be that acceptable to man, and not subject to uncomfortable demands on the part of God. The characteristic thing is bondage to one's human nature rather than submission to the Spirit of God.
. . . . Those words, "I have a right to be happy," perfectly express the mind of the flesh. No matter at what cost to others, no matter at what ultimate cost to himself, the fleshly person claims the right to be happy. All other consideration must be subordinate to that.
The fleshly nature is concerned with self. The Spirit is concerned . . . with the glory of God. Inevitably the two are implacably opposed. As Paul says simply, "they that are after the flesh do mind the things of the flesh; but they that are after the Spirit the things of the Spirit" (Rom. 8:5), and he goes on to remind us that "the mind of the flesh is death . . . the mind of the flesh is enmity against God . . . they that are in the flesh cannot please God" (vv. 6-8). Logically, inevitably, "if you live after the flesh, you must die" (v.13).
But . . . "you are not in the flesh, but in the spirit, if so be that the Spirit of God dwells in you" (v. 9). The last word is not with the flesh but with the Spirit of God (Spirit of the Living God, p. 82-84).