Chakka.. What you call "ordinary, everyday, routine, rational atheism" is based upon science such as radioactive dating showing that the world is more than 5000 years old, evolution being partially written in the phylogenetic ontogeny of every embryo and evolution being obvious from molecular biology etc.
Science, or rather knowledge, shows that the cosmologies described in 1000-3000 year old books and traditions are usually false.
Now take away the cosmologies and focus on moral issues such as the nature of a moral action. Does science have a greater usefullness or accuracy in this area of philosophy than religion? The link I gave in my first post on this thread suggests that simple materialist science is hugely problematical when applied to morality.
You might also consider the form and content of Platonic love rather than the process of love, again science has a problem explaining such things, being about process rather than form.
I think Jake the Peg has alluded elsewhere to the possibility that modern science, which might be more accurately labelled "physicalism" than materialism might provide some foundation for moral principles. However, if we pursue the physicalism we stumble upon possibilities such as universal consciousness and pan-psychism that are not exactly atheist.