And compared to other people, on a horizontal level, most folks are good. No matter how hard we try, we can never be perfect. We can never be true in our hearts to our Creator-God. In fact, the Holy Scriptures teach that believing that we can be good on our own, apart from God, is the greatest sin a person can commit. Our sin causes several problems for us.
Sin causes death.
Before Adam and Eve sinned they would have lived eternally. The entropy of the universe started with the first sin. The death that sin causes is also a spiritual death. It separates us from God both now and eternally. The profane simply can't exist in the presence of the pure.