The question concerning the relationship between the believer and indwelling sin is one of the most theologically difficult to navigate. On one end of the spectrum, there are those who insist that the believer is a new creature with a new nature and ought not talk about the reality of indwelling sin in his or her heart. Such teaching results in either doctrinal or functional perfectionism. On the other end of the spectrum are those who stress the prevailing presence of sin in the believer’s life in such a way that they give the sense that the regenerate are still totally depraved. This idea results in either doctrinal or functional antinomianism (i.e. lawlessness). In order to avoid falling into the snare of either of these two extremes, we must reject both errors and seek out a robustly biblical perspective on the teaching about regenerate and indwelling sin.
In the New Testament, the Apostle Paul gives us the doctrinal categories by which we may come to understand the relationship between the believer and the sin nature. He does so by speaking of “the old man” and “the new man,” “the flesh” and “the Spirit” and of being “under the law” and “under grace.” What has happened to believers by virtue of our union with Christ is best explained by understanding our former relation to Adam and our present relation to Christ. Scripture does this, first by way of explaining redemptive history and then by way of giving experiential implications.