The Sin Nature, Sin, The Flesh, and The Old Man

Romans 6:18-20

And having been set free from sin, you became slaves of righteousness.

I speak in human terms because of the weakness of your flesh. For just as you presented your members as slaves of uncleanness, and of lawlessness leading to more lawlessness, so now present your members as slaves of righteousness for holiness.

For when you were slaves of sin, you were free in regard to righteousness.