Scripture says your old nature was crucified with Christ, so you are not a divided person housing a good self and an evil self. You have one new nature. Sin still tries to work through the flesh, your habits and body, but it is no longer who you are.
The Grace Answer
This trips up a lot of sincere Christians who feel two forces pulling inside them and conclude they must be half saint, half sinner. Scripture tells a cleaner story. Our old man was crucified with Him, that the body of sin might be done away with, that we should no longer be slaves of sin. The old nature was not merely wounded or managed. It was crucified. It died.
So you are not a divided self with a good nature and an evil nature taking turns. You have one new nature, received when you were born again, joined to Christ. That is your true identity now, and it is not up for renegotiation every time you stumble.
Then what is still pulling at me?
The Bible calls it the flesh. The flesh is not a second nature. It is the old patterns, appetites, and reflexes still wired into an unredeemed body and a mind being renewed. It can be loud. It can war against the Spirit. But it is not the real you, and it does not define you. Paul could say sin was at work in his flesh while insisting it was no longer I who did it. The pull is real; the identity has changed.
Think of it like a house under new ownership. The former resident still knows the locks and shows up acting like he lives there. But the deed has changed hands. His familiarity is not the same as ownership, and his pounding on the door does not make him master of the home. This matters pastorally. If you believe you carry a sinful nature at the core, every failure feels like proof of who you really are, and you fight sin from defeat. If you know the old you is dead and your nature is new, you fight from victory, agreeing with what is already true rather than trying to become someone new.
Faithful believers do describe this differently, and some prefer the language of two natures for the ongoing struggle. The struggle is real either way. But the weight of the new covenant lands here: the old man is crucified, you are made new, and sin is now a trespasser in your house, not the owner of it.