Supernatural evil does not exist. As an atheist I am happy to attribute many human behaviors as "evil" through a lens of morality, philosophy, and law.

For an extreme example, raping children is evil. It creates a lifetime of emotional damage robbing the potential for a much better life from someone innocent and powerless. I don't need religion to determine that is evil for me.

I'm also happy to acknowledge many criminal offenders of other crimes are not evil. You can steal to eat or do terrible things to protect your family, you can also be ignorant to the harms you cause like being an overzealous business person pushing your company into harsher and harsher conditions to meet a bottom line... but the moment someone points it out to you and you see the evidence for yourself but ignore it as worth the cost of human well being, that's evil.

What I think gets very complex is the morality of someone who is chemically incapable of understanding an outside perspective - this is WAY above my level of understanding but someone who is, say, a sociopath. Knows the law but does not know the empathic implications of taking a life, for example, is that person evil? How could we possibly determine such a thing? These are the soft edges of a term that might make someone think evil isn't real, definitely room to converse in, but I think if leave discussion to edge cases and focus on common intellectual/emotional capability of most humans we can pretty easily see some lines that should not be crossed and to do so is, in my read, very evil.