he may be different, but he's also god's creation. why are people mean to him?
Because people generally don't like things that are different.
People strive to resolve tension and awkwardness by blending in with what societal norms of the times are, if someone fundamentally contradicts those norms, then it's harder for that person to resolve that awkwardness and tension. Cognitive dissonance and all that.
Or at least that's what they beat into our heads in communications class... >_>