I don't think it's necessary for someone to have "a devotion to the forces of evil" to commit evil acts, and I think you agree with that. While it may be useful to undertsand someone's motives, etc to see where they are coming from, we can still assess their actions as pure evil, and I don't think that 'pure' is defined as "evil for evil's sake" - the definition I think stems from an external observation of the outcome and how corrupt it is, not an assessment of motivations. For instance, you could argue that Satan (and I know you reject Satan as a concept) is justified in his actions because of his relationship with (and to) God. Not a good idea in my book.
Yep, I think we agree in principle. There's a wide berth of opinion on this in conservative circles. I tend to vent about those with the most extreme position, like Sean Hannity and Anne Coulter (talk about evil). People like them really do subscribe to the "evil for evil's sake" argument. It only takes a small amount of intelligence to see that's a moronic position to hold.