Alright, so a writer's thoughts must be understood, of course, not only listed. Look at the following verses. Again, Paul's talking about the will, whether I will be carnally minded or Spiritually minded. I can choose either now, as Jesus opened the door for me to God. The flesh is simply who we are, what we fall to, when we're on our own, apart from the divine. Man is
made for the divine, to be united with God. Otherwise he's lost, sick, dead. The flesh, by its nature, is uncontrolled, impulsive, drawn to whatever attracts it in the moment. Christianity is all about uniting man with God. The sin, the offense, the injustice, of fallen man is his disunion with his Creator. From that state of separation, havoc and chaos inevitably result.
And the reason that believers don't suddenly become perfect is that they continue to be attracted to things other than God first above all else. They're not yet perfected in love, to put it another way. The old man, the flesh, with the false promise that more will be gained, greater happiness will be had if we remain apart from God, still attracts. The sin of Adam, our family tradition, still has its pull on us.
Romans 7: 25 I thank God through Jesus Christ our Lord. So then with the mind I myself serve the law of God; but with the flesh the law of sin.
Romans 8: 2 For the law of the Spirit of life in Christ Jesus hath made me free from the law of sin and death.
3 For what the law could not do, in that it was weak through the flesh, God sending his own Son in the likeness of sinful flesh, and for sin, condemned sin in the flesh:
Romans 8: 5 For 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.
Romans 8: 6 For to be carnally minded is death; but to be spiritually minded is life and peace.
7 Because the carnal mind is enmity against God: for it is not subject to the law of God, neither indeed can be.
8 So then they that are in the flesh cannot please God.
Romans 8:11 But if the Spirit of him that raised up Jesus from the dead dwell in you, he that raised up Christ from the dead shall also quicken your mortal bodies by his Spirit that dwelleth in you.
12 Therefore, brethren, we are debtors, not to the flesh, to live after the flesh.