I would most appreciate Navigator's answer but anyone can play.
Theoretical scenario . . .
An atheist has caused the deaths of some people and is about to cause the deaths of more. You have the ability to cause the death of the atheist to prevent her from causing more deaths of these people that include children, women and members of your own family. Would causing the death of the atheist be good or evil?
ETA - There is no other way to prevent the atheist from causing the deaths than causing her death.
Okay. I will put in my two cents.
Quick answer. I will kill her. I would consider it neither good nor evil. Just something that had to be done.
Afterward I could debate whether it was good or evil, and my view would be my intentions at the time. Her religion or lack of it be not a consideration.
The real life complications.
The first question I would ask is why is this person killing. If she is a doctor doing mercy killings (euthanasia) then I would allow her to kill more. If she is committing murder, then killing her is justifiable homicide (if there is no alternative).
Another complication is how the killing would take place. Personally I would prefer a clean and uncomplicated "push-the-button" method. I have had to put animals out of their suffering, and not many people would be able to steel themselves use the methods left to me. Slice the throat, drown them, bash their head in.
Many people may also hesitate to kill a female. (Nice touch, ynot.)
If on the other hand, the female is a Palestinian with a knife, an Israeli is likely to kill without hesitation because they would reason that Palestinian/Arab lives are worthless, their religion is evil, and there will be no legal consequence. Now the question is: Is that good or evil? And does one have to consider only the immediate circumstances or expand the question to include the history of Israel and Palestinians.
And to make this relevant to the thread - what is God's purpose in Israel or the Arab world?