@InkRune,
It is a good point indeed, but evil cannot be measured as it is not a thing, but a lack of a thing. Like cold is not measurable, as it is our word for a lack of heat, evil is our word for a lack of goodness.
I see the devil working the world over, rather than sitting on every mans shoulder.
A magicians greatest tools are misdirection and illusion, all the devil needs to do is to make Gods will/requirements/standards seemingly disappear. Id say he has done a remarkable job don't you?