Killing is evil in Pathfinder. As is oppression and harming others. Seems odd that outright murder (unjustified killing) wasn't considered evil.And that's the catch. Justification is pretty easy to come by, even before I decided my Mage was on the unethical side of the Objectivist philosophy.
To go back to the items that turn you evil, in that case it's not a stretch to pick up a spell to undo the change while holding onto a useful tool.
Well what I mean by justified killing is a neutral killing. IE - killing that is altruistic or in the defense of life or dignity.
A hero who kills an orc to save the life of someone else is justified. It's not a good act by any means but it's not evil. As opposed to say, killing for profit, fun, or convenience.
I assumed that when you said murder you meant killing that was clear into the deep end of the alignment pool (IE not tied to an act of good). :P
Okay here we go.
It seems a little dishonest to pre-meditatively start thinking about atonement when your about to commit an evil act. That crap should automatically fail. You don't get to be like "Sure lets sacrifice these children now and get the permanent profane bonus to attack rolls then go get an atonement spell to clean up any alignment nonsense."
On the other side, I can believe not losing your ill-gotten benefits. To do so would mean the lives you took or the evil act would have absolutely no meaning. Which in my belief would make it even more vile. I.E Sacrificing some children, gaining some crazy profane ability or bonus that doesn't necessarily cause more harm or evil by use. Giving that up, even though you'd use it for good would basically mean you sacrificed those children for no reason.
In my games, if anyone dared to attempt to gain some benefit from committing an evil act then ask their deity to forgive them, they'd get some righteous smiting. I'm thinking maximized heightened flame strikin.