What does the Bible say about the nature of sin in Christians?

The Bible presents a clear picture of the nature of sin in all humanity, including Christians. As outlined in Jeremiah 17:9, the heart is deceitful and desperately wicked. Believers are born in sin and remain in a state of sinful flesh even after accepting Christ. Romans 7:18 highlights that in our flesh, no good thing dwells, indicating that while believers have been redeemed, they still contend with their sinful nature. This ongoing struggle is part of the Christian experience as they seek to walk in the Spirit, which leads them to live differently, but does not eliminate sin entirely.