The Greek noun (transliterated) Sarx (G4561) literally refers to flesh, but is also used to refer to the depraved appetites of the flesh, otherwise called sin.
An adjective form of the word is "sarkikos" (G4559) and refers to being under control of our depraved appetites, and is applied to both lost people and saved people, with their minds set on fleshly desires.
But another adjective form of the word is sarkinos (G4560) which is used to refer to nonspiritual people of flesh, lost and not indwelt.
Part of the confusion arises from the TR having G4559 at Romans 7:14 and 1 Corinthians 3:1, but the CT has G4560 at these locations. Thus we can understand every usage of G4560 (Romans 7:14, 1 Corinthians 3:1, 2 Corinthians 3:3 and Hebrews 7:16) to refer to unsaved, people in the natural non-indwelt state.
Romans 7:14
For we know that the Law is spiritual, but I am of flesh, under sin.
1 Corinthians 3:1
And I, brethren, could not speak to you as to spiritual men, but as to people of flesh, as to infants in Christ.
2 Corinthians 3:3
being manifested that you are a letter of Christ, cared for by us, written not with ink but with the Spirit of the living God, not on tablets of stone but on tablets of flesh, representing our core attributes.
Hebrews 7:16
who has become such not on the basis of flesh requirement law but according to the power of an indestructible life.
An adjective form of the word is "sarkikos" (G4559) and refers to being under control of our depraved appetites, and is applied to both lost people and saved people, with their minds set on fleshly desires.
But another adjective form of the word is sarkinos (G4560) which is used to refer to nonspiritual people of flesh, lost and not indwelt.
Part of the confusion arises from the TR having G4559 at Romans 7:14 and 1 Corinthians 3:1, but the CT has G4560 at these locations. Thus we can understand every usage of G4560 (Romans 7:14, 1 Corinthians 3:1, 2 Corinthians 3:3 and Hebrews 7:16) to refer to unsaved, people in the natural non-indwelt state.
Romans 7:14
For we know that the Law is spiritual, but I am of flesh, under sin.
1 Corinthians 3:1
And I, brethren, could not speak to you as to spiritual men, but as to people of flesh, as to infants in Christ.
2 Corinthians 3:3
being manifested that you are a letter of Christ, cared for by us, written not with ink but with the Spirit of the living God, not on tablets of stone but on tablets of flesh, representing our core attributes.
Hebrews 7:16
who has become such not on the basis of flesh requirement law but according to the power of an indestructible life.