Some people define evil as causing harm. What harm does the "sins" in Christianity cause?

Most of the "sins" in Christianity cause no harm. If they cause no harm, how can they be evil? If they are not evil, why are they called "sins"?
Update: Naturally everybody coming and going starts listing crimes rather than the "sins" others are so often condemned for.
Update 2: Ellory: You've got a pretty good start. Unfortunately, none of the 'believers' will bother to think it through.
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