"Sin" is an imperfection. Something that is at the core of our being. For example, there were sins "atoned" for that were "unknown" that they were done on the "Day of Atonement." One example of this is called an iniquity. Found here:
"We all went astray like sheep;
we all have turned to our own way;
and the LORD has punished him
for the iniquity of us all."
(Isaiah 53:6) (Emphasis mine)
sin, iniquity, transgression
Chattah, which is most often translated as
sin, means to miss the mark.
Awon, often translated as iniquity, relates more to the inner character and points to an intentional twisting of a given standard.
Pesha, often translated as transgression, is more of a willful rebellion against the given standard. are also used interchangeably
None of the above are good, all are sin .... as it is said.
James 2:10
King James Bible
For whosoever shall keep the whole law, and yet offend in one
point, he is guilty of all. (missing the mark, twisting the law, willful rebellion)
Sin is sin .... call it iniquity, missing the mark or willful rebellion.
Satan and iniquity
Iniquity was found in the heart of Lucifer the originator of sin.
so .... what is the given standard? Gods law .... in which He reveals His perfect character.
Unknown sins? Unknown to us (the secret things) .... but not unknown to God.
Judgement requires law (the standard) all are judged by it .... those who have sincerely repented will be pardoned through the blood of Jesus ... only He knows who they are .... unknown to us.
When we repent, we are acknowledging our need for God's forgiveness and grace through faith ... faith that God will do what He said He would do .... we rest in that and continue our daily walk with Him.