Generally atheists claim to be skeptical of all religion and mysticism regardless of whether it claims a "creator god". If you want to be pedantic and say someone who believes in ghosts, but not God is still be an atheist, well ok.
My point is that almost all people hold unexamined beliefs as non-material and unscientific as any religion. Hence they are not inherently more rational.
> be excellent to each other
I think the rule you are describing is not well defined at all. Are you treating them well because it's right, or because it's a benefit to you? If it's just comfort, then it only makes sense when it's convenient for you, or likely to be reciprocated.
Should you do what makes other people feel good? Or what is actually good for them? After all, it "sucks" when people try to make you do things. How would you know when to violate your rule of being "excellent"?