Since it's possible for act act that harms no Innocents to be evil (torturing the guilty, if you go by various splatbooks) and since a pattern of evil deeds tends to be the mark of an evil-aligned character, I tend to prefer a slightly looser definition of evil-

that doesn't say "If you're torturing people to death for pleasure, and harming their souls, and doing various other vile deeds, you're still Neutral if you're only willing to do this to the Not Innocent, unless you become willing to harm the Innocent as well".

An extreme case- but it does illustrate the point.