Sarx, pronounced as sä'rks is the Greek word for “flesh” in scripture. The two primary definitions, depending on the context of course, are: a. the soft substance of the living body, which covers the bones and is permeated with blood; b. denotes mere human nature, the earthly nature of man apart from divine influence, and therefore prone to sin and opposed to God. (Strong's G4561) When referring to the physical, flesh is a thing and things within themselves “are pure” (Rom 14:20; Tts 1:15). So, Paul’s “I know that in me (that is, in my flesh,) dwells no good thing” is equating his “flesh” to refer to his still indwelling carnal man or old nature. Not his physical body and remember, the bodily flesh is also “the temple of the Spirit” (1Cr 6:19). Through his entire discourse of Romans 7, I believe Paul is stating this after being regenerated, because it required the Spirit to be in him to know this. He also mentioned that it was no longer “I” doing the wrong (vs. 17, 20). I believe the “I” is the “new man” which is now that part of us that is “partaker of the divine nature” (2Pe 1:4) and which is the “seed which cannot sin” (1Jo 3:9). Another indication the he was in his transformed state is the words “so then” (v 25) or “therefore”, which denoted his final state of being.