HI well I think people's sins explain a lot about them and who they really are at their core. This makes people outwardly very simple since sin means to miss the mark. I believe that people feel that their mistakes are quite normal and do not really perceive what it means to miss the mark because everyone misses the mark too. But however, God does not miss the mark, and everything is perfect without mistakes as you can recognize from observing outer space, Romans 1:20. So by using exact perfection God made a decree for humans that live under sin, Acts 17:24-31.