You must have "contrast" or you can't have both; there must be light in order to have dark, etc.
Hermetic Law asks the question, "When is something hot?" What is hot or warm to me may be considerably different to another e.g. they are both the same but different by degree or level of perception. It is a rule of thumb that goes with most everything in life including that thing we face here regularly -- the difference between believer vs. skeptic. The irony being that I admit to being both and it's because of this Hermetic principle. . . I'm also gay but have strong paternal instincts (need) which resulted in my raising 10 kids over the past 30ish years. (in other words, I'm a sucker for a sob story and big sad eyes -- ask any puppy or kitten that's crossed my path)
Most folks confuse "Good v. Evil" with their sense of morality and/or ethics. In some cultures is normal and quite moral to have more than one wife and yet, the anal retentive views of the Judeo-Christian influence on much of today's society leads us to view such things as being a corruption and somehow, breaking of God's law (though you don't find it anywhere in the bible and for that matter, find that most of the great teachers in the old testament actually had several wives, mistresses and "male servants/companions") Nonetheless such practice is now viewed with contempt and seen as a perversion because of a belief and understanding the masses have been programmed to support.
Less than two generations ago it was not viewed with as much disdain and legal judgment when a man beat his spouse & children into submission, it was normal and if we go by the teachings of "Saint" Paul, his obligation (women & children -- especially female children-- were viewed as being "property" in biblical tradition, a mind-set that really didn't get "shifted" until the latter 1960s and 70's when it comes to most of the Western culture, there are still some ugly exceptions). Today, if you swat a misbehaving child on the rump with your bare hand or slap their hand, etc. you can be jailed, the child placed into state custody and you stigmatized as being an abusive parent around whom no child should be without a supervisor. . . in other words,
proper parenting has become "evil" in today's passive-minded world where it was previously (within my own youth) seen as proper and a moral obligation. . .
Spare the Rod, Spoil the Child.
Truth Is (when it comes to Parenting) every child is different and every child must be handled differently; spanking works for some children while a raised voice is all you need with others. I find it ironic that a Gay man knows such things while millions of "straight" parents who think themselves "more qualified" and of course "morally justified" to raise kids, don't have the first clue.
So yes, Good & Evil are a matter of perception but both must exist, at least in our minds and culture, not just as a measure for morality and ethos, but for the sake of effective conveyance & description.