Again? You didn't understand, verse 8 comes
before the cleansing, all have sinn
ed in the
past, all need to confess and forsake, but after beeing cleansed from
all unrighteousness, you are cleansed from
all unrighteousness, because "all" means "all".
All unrighteousness is sin, if Jesus cleanses us from
all unrighteousness, then we are cleansed from all sin, because of the abstinence of all unrighteousness in us, we become therefore, righteous, doers of righteousness:
1 John 3:7 Little children, let no man deceive you:
he that doeth righteousness is righteous, even as he is righteous.
But If you continue in sin after beeing washed you are liken unto a dog returning to his own vomit, you are still in need of repentance.
Confess and forsake. Until you "abide in Him":
1 John 3:6
Whosoever abideth in him sinneth not: whosoever sinneth hath not seen him, neither known him.
9
Whosoever is born of God doth not commit sin; for his seed remaineth in him: and
he cannot sin, because he is born of God.
1 John 2:4 He that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him.