To become Good, you have to become human, and to become human, you have to understand evil.
And by understand, you need know intimately what it feels like, why and how it makes sense, what problems it solves, and where those problems exist within you.
So much evil is done in the name of Good that Goodness itself has largely come under attack as a meaningless word.
This is, of course, ludicrous, and the product of inferior minds.
But it is worth remembering that all of us have the capacities of all of us. All of us have both Ted Bundy and Albert Schweitzer in us.