Satan was brought up amongst Gods heavenly family we could call it, despite being perfect he also had free will. Satan chose to go against gods will even though he knew better. Because of this fact God does hate Satan and his demons, they have willingly disobeyed Jehovah and therefore are worthy of death.
As for those who follow satan it all depends if they have come to an accurate understanding of the scriptures. We've heard the saying with understanding comes responsibility, well the same thing applies with us. If we know what we should and shouldn't do according to the scriptures, yet we choose not to apply it, then we are wilfully sinning against God, something he wont tolerate. But if we were to have no knowledge of the scriptures and lived a wicked lifestyle Jehovah would show mercy seeing that we didn't know any better. But upon finding out what God does require of us we would have to choose which path we would take, to keep leading the same life or to make drastic changes so that our lives are in harmony with Gods word.