For I (new nature) intuitively know that dwelling in me, that is in my flesh, is no good. For the desirous will is present with me (new nature), but the working out of the proper, it is not found. (Romans 7:18).
In Romans chapters 6 through 8, Paul discusses the sin nature, how to overcome it, the impact of the Law on the ability to live out the Christian life, the frustration of trying to live according to the flesh, and the victory we have in Christ. In Romans 7:15–20, Paul refers to the internal conflict between his old nature—in Adam—and his new nature in Christ.
To assist with identifying which nature Paul is referring to in each instance, “old” or “new” has been noted beside the relevant references.
7.15 For that which I (old nature) work out, I (new nature) do not experientially know, for that which I (new nature) do not desirously will, this I (old nature) practice, but that which I (new nature) am indifferent to, this I (old nature) do. 7:16 But since that which I (new nature) do not desirously will, this I (old nature) do, I (new nature) together say with the law that [the law] is proper. 7.17 But now I (new nature), on my part, no longer work it out for myself, but the dwelling in me sin [nature]. 7:18 For I (new nature) intuitively know that dwelling in me, that is in my flesh, is no good. For the desirous will is present with me (new nature), but the working out of the proper, it is not found. 7.19 For not that which I (new nature) desirously will, to do good, but that bad which I (new nature) do not desirously will, this I (old nature) practice. 7.20 But since that which I (new nature) do not desirously will, this I (old nature) do, it is no longer I (new nature) working it out, but the sin [nature] residing in me.