The "flesh" stands for a certain orientation of life. It is the sin-bent self characterized by self-sufficiency that wages war against God… The flesh and the spirit denote not two coexisting parts of the individual, but a contrast of tendencies and loyalties which compete for dominance as powers within each person… It creates estrangement from God that is broken only when persons submit in faith to the gospel and allow God’s Spirit to seize control.
A Christian is truly regenerated – but at the same time only partially sanctified. Sin is dethroned – but not destroyed! His predominant taste and disposition are holy – but godly principles may not yet have struck their roots very deep into his soul. His holy purposes are somewhat vacillating, and his inclinations to evil sometimes strong. We have the burden of our fleshly corruptions to carry, which without great labor and effort, will sadly retard us in our Christian lives.
The flesh is the old life, the natural life inherited from Adam, with its apparent resources of personality, of ancestry, of commitment, of dedication, and so forth. You can do all kinds of religious things in the flesh. The flesh can preach a sermon. The flesh can sing in the choir. The flesh can act as an usher. The flesh can lead people to Christ. Did you know that? The flesh can go out and be very zealous in its witnessing and amass a terribly impressive list of people won to Christ, scalps to hang on a belt. The flesh can do these things but it is absolutely nauseating in the eyes of God. It is merely religious activity. There is nothing wrong with what is being done, but what is terribly wrong is the power being relied upon to do it (Ray Stedman).
Flesh is the old ego that is self-reliant and does not delight to yield to any authority or depend on any mercy. It craves the sensation of self-generated power and loves the praise of men.
The flesh is the ego which feels an emptiness and uses the resources in its own power to try to fill it. Flesh is the “I” who tries to satisfy me with anything but God’s mercy.
So deeply planted are the roots of human corruption, that even after we are born again, renewed, “washed, sanctified, justified,” and made living members of Christ, these roots remain alive in the bottom of our hearts, and, like the leprosy in the walls of the house, we never get rid of them until the earthly house of this tabernacle is dissolved. Sin, no doubt, in the believer’s heart, has no longer dominion. It is checked, controlled, mortified, and crucified by the expulsive power of the new principle of grace. The life of a believer is a life of victory, and not of failure. But the very struggles which go on within his bosom, the fight that he finds it needful to fight daily, the watchful jealousy which he is obliged to exercise over his inner man, the contest between the flesh and the spirit, the inward “groanings” which no one knows but he who has experienced them – all, all testify to the same great truth, all show the enormous power and vitality of sin. Mighty indeed must that foe be who even when crucified is still alive!