My opinion is this: if a person realizes that they are doing something wrong, then they are evil. As for Nowizard's examples: if the Inquisition is not evil, then Satanists are not evil either – they also believe that they are doing the right thing; a man got drunk out of grief and beat his wife – but why did he drink in the first place? Alcohol won't make things better, and the problems won't disappear; they will most likely only get worse (it's a pity that not everyone understands this); regarding the embittered person – someone great said: "Revenge is good only if two conditions are met: if innocent people do not suffer as a result, and if it does not become the meaning of life." P.S. And please try not to promote any religion.