'Sinned' in the Bible

If we [freely] admit that we have sinned and confess our sins, He is faithful and just [true to His own nature and promises], and will forgive our sins and cleanse us continually from all unrighteousness [our wrongdoing, everything not in conformity with His will and purpose].

If we say that we have not sinned [refusing to admit acts of sin], we make Him [out to be] a liar [by contradicting Him] and His word is not in us.

The one who practices sin [separating himself from God, and offending Him by acts of disobedience, indifference, or rebellion] is of the devil [and takes his inner character and moral values from him, not God]; for the devil has sinned and violated God’s law from the beginning. The Son of God appeared for this purpose, to destroy the works of the devil.