The concept of "evil" has way too many logical problems. Terms such as morally right & morally wrong would perhaps be better. Although morals are relative and subjective, that doesn't make them any less real. They're a foundation of every society; every society has its own set of morals.

"Evil," on the other hand is a really strange concept, inside and outside of religious context. Would you consider a psychopath who commits a murder evil? You do know they're born with a disorder, right? It's his nature. Would you call a tornado evil? That's a natural phenomenon.

Point being, to call someone or something evil is, by proxy, calling nature evil. Good and evil are social constructs, rather poorly defined ones, at that. They do not exist in nature (this also applies to morals btw, except they're better defined).

But here's where the terms "morally wrong & morally right" come into play. You can say that the murder that the psychopath perpetrated was immoral, because the act itself is a violation of (the most common) moral principles.

But can you call a tornado immoral? No, you cannot. Why? It has nothing to do with society. It's simply a natural disaster.