My evidence is the world itself. Who do we look up to, who do we respect? Not the most religious people... but the most loving and caring people. We get that amazing feeling when we do something truly selfless, and feel that tinge of guilt when we carelessly hurt someone. THAT is what our conscience is. Our conscience doesn't have the word "Jehovah" built in.
As for my image. It is not negative, nor violent. Although I feel that either way you would not understand, I will explain why I don't feel it to be scary. It represents a part of life, that is to say, death. Death is just another scene in the unending movie that is our life. We are here to learn, and to progress, all in love.
In the tarot, there is a card named "Death". It scares a lot of people initially, but what it represents is actually a quite beautiful thing. Although death is the end of something, it is also the beginning of something else. Throughout our lives, we die and are reborn numerous times, through experiences. Ever heard the expression "It changed my life"? That is what death is, it is a rebirth, a growing into a new life.
So, that explains why I do not feel the avatar to be negative, now for the reason I actually have it as my avatar... it was my halloween makeup and I thought it looked cool. Simple huh? Like so many other things in life.