Sorry, you got atheism wrong
You're right that many atheists fall into the trap that you describe, but you're wrong about why it is wrong.
The theory of evolution is about a process of change, yes, but that rate of change generally goes faster than the environment that organisms are attempting to adapt to. Therefore most of the time, most organisms are pretty well adapted to their current environment and do not have any obvious improvements (or they would have made them).
Therefore even though evolution is a process of change, at most times it predicts that things should stay pretty much the same. And if it doesn't predict that, then there should be a good reason why things just changed.
Now clearly the impact of society and technology has gone faster than evolution, and we as a species have not caught up. But it is dangerous to shove through that hole all of our wishes that people would be different. Down that path lies a long history of bad thinking - study the history of Social Darwinism for a sample.
For the real reason why that thinking is flawed you have to understand that there are many different norms that we are dealing with, and they are not equivalent. They are not even well correlated!
Evolutionary success is entirely predicated on having lots of descendents. Period. In our society traits that are selected for include being Catholic, being on welfare, and not being particularly careful with birth control. Traits that are selected against include wanting a career (particularly for women).
This kind of success has nothing to do with success as materialistic society measures it. In fact the two are negatively correlated - someone who has raised lots of kids is unlikely to have had the time and energy to have had a stellar career.
And both those kinds of success have nothing to do with any kind of socially accepted morality. For instance a successful serial rapist might be evolutionarily very successful (though the police will try to limit his success), but certainly is not a moral exemplar.
So avoid the word "best", or if you use it, stay very aware of what standard you're measuring goodness by. Because people have a tendancy to not be very clear on the fact that best is often not very good (after you switch norms), and this leads to confusion.
Cheers,
Ben
PS Welcome. It is always nice to see a new face - particularly one who takes a novel tack on familiar topics.
I have come to believe that idealism without discipline is a quick road to disaster, while discipline without idealism is pointless. -- Aaron Ward (my brother)