In the religious context, good and evil are merely the presence or absence of the divine spirit in our lives. It is a decision, meaning we create our own good and evil, by our decision to be in or away from God's spirit.
In the secular context, I think we have decided to enact codes and laws from ancient time to identify minimum standards of behavior, whether the Ten Commandments' "thou shalt not kill," or the Uniform Commercial Code's implied warranties of suitability and fitness for a particular purpose. So lawbreakers are viewed as "evil," and law keepers are viewed as "good."
So getting back to the original point. I do not think there is an immutable "good" or "evil" floating out there in space. I think "good" and "evil" are what we define it as a society, and as individuals. Like Roy Moore, evil motherfucker.