It is true that the believer, by God's grace and mercy, has been forgiven of original sin. Yet, in spite of the forgiveness of sins, sin remains a very real facet of the believer's life on earth. The child of God experiences sin as an inescapable reality of daily life, and this bothers the child of God. Sin is not simply a misdeed. To equate sin with a misdeed is to underestimate what sin really is.
Sin is far more than making a mistake.
Sin is rebellion , rebellion against God's God-ness, rebellion against my needing to submit to Him as God. Sin, then, is not just an outward deed, but sin is an attitude of the heart . Hence all my mistakes and misdeeds are expressions of what is in my heart. No matter what I do, it is covered with sin because of my attitude of rebellion. After David acknowledged his transgression before the Lord in his affair with Bethsheba, he asked himself where his sin came from.