Problem of good and evil for an atheist

[ChromodynamicGirl]

Whether you like it or not. There ARE things which are absolutely evil and things which are absolutely good.

Whether or not you like it, there are not things which are 'evil' or 'good' at all. These words do not mean anything, they're tropes for social signaling and psychological triggers. Just projecting your evolutionary biases onto the Universe. Reality doesn't give a shit about your fantasies.

I know most atheists atempt to discredit this idea (There is a huge problem if there is such thing).

I wish most atheists would try to discredit this idea. Instead they spend all their time being moral masturbators; they've replaced the theology of God with the theology of Humanism. Our atheists are pious people.

So what is one example of something absolutely evil?
Killing a baby, an innocent baby for any reason is evil. (please dont derail this thread with attacking the Bible)

Nonsense.

If you think killing a baby is ever justified, I think it is safe to say, that you are sick and perveted.

You're stupid if you think it makes sense to repudiate morality and talk about 'justification'. Nothing is 'justified' or 'unjustified'. It's all just your personal feelings. I also love your circular reasoning here, "Everyone agrees that killing babies is evil, and if you don't there is something wrong with you."
Idiot.

Some cultures did practice killing babies, however, we would call them 'immoral'.

Perhaps you would. I don't really care. Besides, eugenics are underrated. What good are retards, really?

Since we are the only creature on this planet, who has the ability to do evil and good and not just to respond to external stimuli. This notion of good and evil had to come from somewhere.

Well, as I explained, 'good' and 'evil' don't exist; and humans (just like everything else) operate on a mixture of internal machinery and external stimulai. Whether or not you like it, we are animals, and machines. We just have some fancy (if ultimately disappointing) cognitive gears spinning around in our heads.

Evolutionarily speaking why should I care if a child was killed in Africa?

I don't. I couldn't give a damn about that. However, if you're looking for 'why do most people respond to this' it has to do with sociobiological tropism, evolved herd characteristics which integrate with cultural cues and social signaling practices. You're also stupid if you think there is some direct connexion between cognition and your biology; even if it didn't make any sense for your DNA's sake your DNA is not conscious and intentional; it has no opinions. What you have are a slapdash of feelings and thoughts which, historically, have assisted the survival of your DNA. There is no high-precision engineering going on in human beings, just recipes.

There is no natural explanation for the concept of good and evil. So where did it come from?

Imagination. Fantasy. Evolutionary psychology. It's bullshit, but people believe in it because they're built that way. Just like they usually believe survival is inherently desirable.

I personally think it came from a cosmological battle between good and evil, although I cant conclude and prove that it, it explains things much better than anything else.

That's not even an 'explanation', that's magical nonsense which means nothing, entails nothing, predicts nothing, and models nothing.
"I personally think it came from an unknowable battle between nonsensical forces in a manner which can not be described."
Will you people go extinct, already? You clutter the world.