How relative do you think the topic of Good and Evil is?

To begin, for the longest time I've been thinking about this and something a very important person told me essentially was that I wasn't a good person. Now that doesn't really irk me, but again, as someone who is philosophically minded, I just want to know how everyone feels about the relativity of these two qualitative words and how they would distinguish the two. Another reason why I've been thinking about this, and more likely the real one is I'm a pretty big nerd and love the original series of star trek :P. They had an episode, "the Savage curtain" discuss this topic in a pretty fun way. Watch the episode to understand what I mean :P