When I consider the idea of sin I do not see black or white,big or small..God has rules; and He has placed them in a manual called the Bible. Whether or not one reads the manual is irrelevant. The rules are there,just like those for traffic.Run a red light and it may cause you millions of dollars in injury and maybe even imprisonment for vehicular homicide. At another time, you may escape the law or think you did because of no negative consequences.
As far as God is concerned,He finds sin offensive. In Isaiah 1 He says that if your sin is as scarlet or crimson,He can cleanse it. All you have to do is confess it. God does not deal with His creation unjustly. He is a just God and does not respect any person.Everyone is chastised for sin. Often people think sin is what we do. That is correct; but it includes what we neglect to do.
Everyone has a conscience; and though some may not listen to it ,conviction has a voice.Three stories I like and regard as favourites are:
the woman caught in adultery
the woman at the well and
the thief on the cross.
They speak of accusation, secret sins and public punishment with an acknowledgement of sin. Everyone falls within these three groups.All sin and need the compassionate mercy of God.