And in Ephesians 4:22-24 Paul says a true righteous and holy new self was created in us by God. In 1:13-14 he also tells us that the Holy Spirit sealed this in us as a guarantee for our inheritance. Jesus said He would never leave or forsake us and he said that when the comfortor comes He will guide us into all truth. And when we are one with him in spirit, how can we ever say that we are on our own?
Read 2 Corinthians 5:16-17, we are not supposed to ever think of ourselves as being in a sin nature but that we are a new creation. The old has gone and the new has come. We are to think of ourselves after the new born again spirit God created in us. We are the righteousness of God in Christ, we are not to identify ourselves as sinners saved by grace and still beholden to a sinful nature. Our nature, in spirit, has changed, and that is what we are supposed to change the attitude of our minds to. You can't do that when all day long you are thinking of yourself as a sinner.