In a sense, the Jedi and the Sith are different sides of the same coin. They are the extremes of what some may say is the same ideology. The Jedi believe in control over themselves, their emotions, and control in everything else in the Galaxy through peace. The Sith, on the other hand, believe in power; power to shape the Galaxy as they see fit. And while the Jedi believe that anyone should have the power of control over their lives, the Sith believe that anyone should control the amount of power they can individually achieve.
Now, there is a fine line between power and control, and in moderation, neither of them are evil. What makes the Sith evil, because all of them are, is the Dark Side of the Force. While the Light Side is channeled with feelings like serenity, honesty, empathy, and love, the Dark Side is accessed through fear, anger, hate, envy, and suffering. These negative emotions, further fueled by the Dark Side itself, are what make the Sith both so powerful, and extremely dangerous.
Read the full list!