In The Ascent to Truth, Thomas Merton introduces the concept of the "false self" vs. "true self". The false self is who we perceive ourselves to be; the true self is who we actually are. There is generally a huge difference between the two. C.S. Lewis picks up this idea with a slightly different twist: the false self is who we are in our fallenness; the true self is who we are created to be...it's our redeemed nature. Though I won't get into the full complexity of the idea here, it's really very important to understand it because it explains a lot about the conflict we experience, not only within ourselves, but with each other. Both types of conflict are assumed biblically; both are explicitly addressed by Paul, Peter, James, John and the author of Hebrews. The idea is that conversion to Christianity introduces the true self with the advent of the Holy Spirit in our lives. From that point on, we struggle with who we are vs. the person God has redeemed. There is no dualism implied here...we are still one, who animated being who is either completely redeemed, or not redeemed at all. We can't do something bad, then blame it on the false self; there is no Christian "one armed man" to pin our crimes on. The point is, this struggle is normal, and in fact, if there's no struggle, it's not because you've won the battle. It's because you've given up. That's the idea expressed in Romans and Ephesians. The good news is that there's nothing wrong with this struggle...there's no condemnation between the Spirit and the flesh, as Paul puts it in Romans 8:1. We engage the struggle. Where there is struggle, there is Spirit.