It is not like breaking a taboo where it does not matter whether you mean to do it or whether you don't. While there are definite standards of right and wrong, God only judges us on our honest understandings of what is right and wrong. Sin of course also involves disobeying God as we heard in the story of Adam and Eve. When there is no God, there is no forgiveness apart from occasional human forgiveness. We say that nature never forgives, that is absolutely true.
Humans sometimes forgive.
God always forgives provided there is genuine sorrow and repentance. Also, sin is a very strong Catholic tradition. There have always been sinners in the Church and there always will be, please God. The Catholic Church is not just for perfect people. None of us are perfect.