Trembling as I face my own accountability as an atheist, I approach the first of the four questions atheists will not address.
“If rationality and goodness is instilled in people based on evolution, then why do people go against the very survival-striving instincts we have and behave the opposite (both as individuals and regarding humanity as a whole). I’ve yet to meet anyone who has successfully lived up to THEIR OWN standard of goodness.”
First, just to see how hard it would be to find an answer to this question by himself, without carting it around to atheists, I went through the excruciating effort of typing it into google and hitting enter. I timed myself. In 97 seconds I came across the wikipedia entry on Control Theory. Note to all Christians out there who want to ask me questions: please try to find an answer on your own before asking me.
Second, why is this relevant? Even if I had no idea whatsoever how to answer this question, that would prove what, exactly? How is this at all relevant to the existence of god? If it’s not relevant to the existence of god, why pointedly ask why atheists never tackle it? You may as well ask why atheists never tackle the problem of why tacos are delicious.
Third, have you ever taken this question to a biologist or a neuroscientist? Most people, not just atheists, have not tackled this question because most people are uninterested in the answer. People note that they and their neighbors have varying moral codes that change based upon the experience gained from past moral choices and that is sufficient for them. Experts in relevant fields have a chance of answering these questions, yet I suspect you are in the habit of submitting them to music majors like me. This tells me quite a bit about how genuinely you want an answer.
To answer your question, so far as a non-expert can (which shouldn’t dissapoint you if you’re really seeking an answer, because that’s who you asked), it starts by examining our desires. Our desires evolved at a time when circumstances were different than they are at present. For instance, there was a time when eating anything that tasted sweet was a pretty smart idea, since sugars were in short supply. Though natural selection understandably provided us with that trait, today it works against us. Because our environment is in flux, having desires that sometimes conflict with our good senses is what we would expect to see if evolution were responsible for the diversity of life on our planet, but not at all what we’d expect if a god designed anything (unless that god was a real jerk).
This means that while it may make perfect moral sense (in that it will make us happier) to eat healthy, sometimes our brain is running a pre-programmed script built into our DNA that is at odds with reason. This means we are sometimes faced with both the desire to do what is rational as well as the desire to succumb to the irrational impulse. Sometimes we abide by the wrong one.
The same can be said of something like stealing. Compassion is an established quality in countless species that share an insanely high percentage of their DNA with us, and it makes perfect sense as a selectable trait via natural selection (groups that do not kill, maim, or steal from each other would necessarily survive better). However, we also have other desires that can conflict with it. If somebody has plenty of food while you and your family are in danger of starvation, you may very well steal, even though you probably wouldn’t do that if your physiological needs were being met.
This answer is based on a layman’s understanding of evolution and two seconds of observation. Yet it is based on far more evidence and has far more explanatory power than the notion that a god who wanted us to behave a certain way created us with the impulse to act otherwise such that, by your own admission, nobody has ‘successfully lived up to THEIR OWN standard of goodness’ (even if their own standards are taken from an ancient book).