According to Ethics, there are three determinants of what is morally right or wrong: the end of the doer, act of the doer, and the circumstance.
Killing a priest (Amorsolo's example)
end: to take his money. EVIL
act: killed him. EVIL.
circumstance: you wanted to maintain your social life and you're running out of money. EVIL
Then, killing a priest is morally wrong.
Anyway, just wanted to show how the 3 determinants is used. Ethics is a tricky subject when it comes to determining what is right or wrong.
If you come to think of it the concept of good and evil has its own purpose. If we were all the same and did only evil (like killing), the human species might have been extinct by now. It would be so easy for us to kill one another.