In that case though your character is acting, pretty much, either amorally or they are acting out of ignorance.
They *know* the spell is evil but *do not know* why the spell is evil. Namely they don't know what the spell might be doing that they don't know about, also known as, they don't know the reason the spell is evil.
This could be out of hubris, for example, "I don't see why it's evil so I am going to do it anyway! I do what I want!"
False on pretty much all accounts. She's acting very morally, and she does in fact know why the spell is evil. Because like all evil aligned spells it is either using the raw essence of evil to repel its opposite, or it is calling or deriving power from a creature that is from an evil-aligned plane.
Also, she is by definition, acting very moral. In fact, she is not willing to compromise on her morals.
Then, of course, if the backlash of... What does that character do once they find out that the spell does something horribly bad? Namely that it causes people to die, or that it somehow bolsters the forces of evil in a way not previously known. Do they sit back and go, "Ho-hum, I didn't know. Tee hee. I guess I'll stop now."
(Which wouldn't work because the comeback response would be, "You knew the spell was evil when you cast it, people tried to tell you it was evil, and you kept doing it anyway you monster.")
Or do they have a crisis?
Except that the spell doesn't do anything except what it says it does. That's how magic works. You can't judge others, players or otherwise, for stuff you made up, or nebulous maybes and what-ifs. Don't be dumb.
That's about as valid as if I ran out and told two guys they can't be kissing each other because "You don't know what sort of things this will bring about, and even though I have no evidence for it, what you're doing is wrong because it doesn't fit my head-cannon".
There's nothing that verifies the claim that casting protection from law somehow empowers the forces of chaos, or casting magic circle against evil to trap an elemental means an angel somewhere gets its wings. So...that's a dumb argument.
Me... If I found out that I had been hurting people my whole life because I refused to pay attention to facts... I'd be in a bad place.
Fact? I don't think that word means what you think it means.