I agree with Feragnosis. 'Good' and 'evil' are concepts of man. Morals are different depending on a variety of factors, so the idea of 'evil' would be different for each person. Take WW2 for example, most Germans at the time felt they were good and the Jewish people were evil, subhuman even, so the horrors they did weren't 'evil' in their eyes at the time.
To use one of my favourite quotes 'Normal is an illusion. What is normal for the spider is chaos for the fly.'
But, do I believe you cannot kill an idea? No, someone can pick up a book and see inspiration, be it for good or evil.
One will never win. Good cannot exit without evil, light cannot exit without darkness, they're two polar opposites, to know one you must know the other. I believe in balance. You moral will determine what is good and evil and your actions keep the two in check. You might choose to live a good life, but everyone slips up, one day you might yell at someone and say some harsh things. Same with a rather bad person, they may hate humanity, but love his pets. Nobody is 100% good or evil, just what we view ourselfs as in our own mind.