“What is “Sin”?”
Anything I disagree with.
By itself, that is moral anarchy, every man doing what he feels or reasons is right in his own eyes, with not supreme standard to hold him to, even if somewhat interpretive.
How would you feel if or when your children act according to your basis for morality?
Granted that is that supreme moral standard is deficient or can be reasonably shown to be wrong than dissent would be justified, but it is not even practical to have no supreme moral standard to work from.
And which I hold is the Bible, understood in the light of Christ.