@Thomas,
Completely wrong Thomas. Your dictionary does not agree with you. There is nothing in the dictionary definition you provide that says anything about harming or helping people.
It talks about "religious or moral law". Quite frequently you can find religious or moral laws that hurt people far more then they help.
Once you get into the realm of "religious or moral law" you leave the realm of reason. Everyone tries to say that their particular deity or philosophical dogma links reason to some universal moral law. These belief systems that try to claim some universal truth are equally flawed whether you call them "religious" or not.
Faith is a belief in something that is based on some inherent truth that is not proven, but just accepted.
You can't have sin without faith.