Atheist's/evolutionists: If murder furthered my chances of survival wouldn't that be a good thing?

If I don't believe in a personal creator but I do believe that we just evolved over millions of years, wouldn't murder be justifiable as long as it improves my chances of survival? If what's needed for evolution is the survival of the fittest- murder is justifiable, right? What if I choose not to submit to a Government, I would have the right to do that since I'm just my own person in this process of evolution and that there's nothing that actually requires me to submit to any authority, right? If someone is living a so-called "good life" and I choose to murder, what would make me any different than them? If it's impossible to establish a universal objective standard for humanity considering people all possess different subjective standards- which would be the case if there's no creator establishing an objective standard, because mankind's objectivity is always based on their subjectivity first in order to establish laws that they declare as "just"- why are anarchy and murder always being condemned by Atheists?