The word flesh is basar in Hebrew and sarx in Greek. This word is often seen in the Bible and is used in various senses, but chiefly in reference to an unregenerated person. If we take a look at what Paul has said, we shall have a clear insight into its meaning. He said, "I am fleshy" (Rom. 7:14). It was not only his nature or merely any one part of his being which was fleshy; it was "I" as a person, the whole being of Paul was fleshy. In verse 18, in further clarification of his meaning, he declared, "In me, that is, in my flesh." It is very clear here that the flesh in biblical usage refers to all that is in man when he is still in an unregenerated state. Apart from such usage, it is sometimes used (1) in reference to the flesh of the human body, that is the soft part of the body besides the blood and the bones; (2) to denote the human body itself; and (3) to denote all the people of the world. These several different connotations are interlinked one with the other. In the beginning man was created a tripartite being, consisting of spirit, soul, and body. The soul, as man's personality and feeling, on the one hand, affiliates with the physical world through the body, and on the other hand, affiliates with the spiritual realm through the spirit. Thus, the soul has to decide whether to submit to the spirit, so as to be identified with God and His will, or to yield to the body and all the temptations of the material world. At the fall of man, the soul rejected the authority of the spirit and became enslaved to the body and its lustful desires. This is how man became fleshy. Since the spirit has lost its noble position and become a captive, and the soul is subjected to the power of the body, man is regarded in the Bible as being fleshy, even as having become flesh. As the soul is subjected to the flesh as its bondservant, so all that is of the soul has become of the flesh.
(1) The human body consists, as it is, of flesh, bones, and blood. Flesh is that part of the body which is full of consciousness, and it is through the flesh that we receive our feelings of the physical world. A fleshy person is therefore one who follows after his world-consciousness. What the flesh consists of is not "flesh" alone, although it includes "flesh," but also the man who walks after the consciousness of the "flesh."
(2) The human body, whether dead or living, is flesh. But in the spiritual sense, "flesh" refers to the body which is alive, and the life that makes the body alive. From the passage quoted below from Romans 7, we know that there exists a relationship between the sins of the flesh and the body of man: "But I see a different law in my members, warring against the law of my mind and making me a captive to the law of sin which is in my members" (v. 23). In chapter eight the apostle goes on to discuss how one can overcome the flesh. He says that if you wish to overcome the flesh, you need to put to death the practices of the body "by the Spirit" (v. 13). Although the flesh consists of the soul and the body, there is nevertheless a particular connection between the "flesh" and the physical flesh, that is the human body. Consequently, the Bible uses the word sarx in speaking of the flesh in the physical sense, and employs the same word in speaking of the flesh in the sense of the psyche.
(3) Whatever there is in man is born of the flesh, and for that cause he is fleshly. No man in the world is regarded by the Bible as non-fleshly for all men are subjected to the control of the flesh (comprising the soul and the body). They all walk after the sins of the body and the self of the soul. So when referring to all men, the Bible does not say all men but "all flesh." Since all men are fleshly, the word sarx is used in speaking of the carnality of man as well as of man himself.