Measure sin by the law, and it leads to self-righteousness and legalism.  The Pharisees were a glaring example of that.  Jesus taught us that the essence of sin is the failure to love; it is the message of the whole Bible.  When I examine my heart by the Great Commandment, then I find there is always something I need to confess.  Looking back, I always find some way, some person or some time when I have not loved as my Lord has taught me.  It breaks my heart.  There is spiritual progress in the contriteness and confessions of our failures to love as we ought.

“Jesus replied: ‘Love the Lord your God with all your heart and with all your soul and with all your mind. This is the first and greatest commandment. And the second is like it: ‘Love your neighbor as yourself.’  All the Law and the Prophets hang on these two commandments.” Matthew 22:37-40 (NIV)