First, I understand the argument that "you don't need heaven or hell to be moral". That's not the question.
Second, this question is about atheists and non-religious people.
You see many of these people doing good things in their lives continuously with no promise of heaven or any self-benefit. Someone might spend their life working on something that may be only useful in the next century without gaining any benefits. Someone might use all their wealth to help others live better lives with no benefit to themselves whatsoever. Someone sacrifices their own lives or limbs for their country without any promise of going to heaven.
So, I understand that you don't need the promise of heaven to do these things. People do them because they look at them as goals (helping others) instead of means to get to their goal (heaven, being closer to their god, etc). I get that. I also think the same way.
The question is, how does this way of thinking construct in someone's mind? And why?
Have you ever thought of this?
I can answer it in evolution terms: We are evolved creatures and our main difference with other creatures is our brains. We are the most (known) intelligent creatures on earth. Our intelligence allowed us to stop living by Darwinian principles and try to change our own course of evolution. This made us aware of other values, besides maximizing the probability of passing on our genes to next generations. Values such as the long term survival of our kind (as opposed to Darwinian evolution's blind force), importance of non-physical concepts such as ideologies, countries, etc. So in terms of evolution, our intelligence allows us to develop values which cannot be explained in the personal benefit->act relationship.
BUT philosophically, how do these thoughts/values construct? Where do they come from? That's the question.
I would really appreciate if you could help.