To understand why your character is driven toward a certain goal, get to know their positive and negative traits, as well as any significant emotional wounds that might be motivating them. Then you can explore the various kinds of conflict that could block them as they move toward their goal.
A character with this motivation despises the moral status quo and wants to destroy it using its antithesis: evil. Maybe the character admires evil and wants to displace good with their preferred value system. Maybe they know that the most effective way to hurt good people is through the means most repugnant to them. Whatever the reason, their methods are often as bad as the desired outcome.
HUMAN NEED DRIVING THE GOAL (INNER MOTIVATION):
There are five basic human needs that, when missing from a character's life, could motivate them to pursue this goal. The following needs are all possibilities, but only one of them should be the primary driver for any given character. For more information on the relationship between human needs and outer motivations, please see this Character Motivation tutorial.
Self-Actualization: Just as a person believing in good will fashion their life around that moral code, a character who believes that evil is right may pursue it as a way of living up to their full potential.
Love and Belonging: A character without true love or acceptance may come to identify the concept of love as a construct of the traditional "good" moral code. In this case, the character may rebel against it by embracing evil.
Safety and Security: If the character was made to feel unsafe and blames those who typically uphold righteousness or goodness (the church, parents, police, etc.) for that lack, they may decide that evil is actually the safer bet.
Physiological Needs: Near-death experiences have a way of changing a person. A character could alter his way of thinking and the course of his entire life if he sees a threat to his survival as coming from or not being protected by those who claim to be good.
HOW THE CHARACTER MAY PREPARE FOR THIS GOAL:
POSSIBLE SACRIFICES OR COSTS ASSOCIATED WITH THIS GOAL:
ROADBLOCKS WHICH COULD PREVENT THIS GOAL FROM BEING ACHIEVED:
TALENTS & SKILLS THAT WILL HELP THE CHARACTER ACHIEVE THIS GOAL: