What IS good, and how do we determine it?

[comet]

This is kind of a spinoff of the WHY BE GOOD thread.

The question I have for atheists, isn't "why by good." I think it's simplistic and deeply flawed to think that the only reason to "be good" is to avoid Hell. And of course, I believe that anyone can be a good person regardless of beliefs.

The question I have for atheists is how do we know what IS good?

Religious or not, we all somehow know that certain things are intrinsically, universally immoral. Let's use murder as an obvious example. So if murder is wrong, where did this law come from? If this is a universal truth, where did this truth come from and who/what determined it to be what it is?

we do the best we can with each other.  And using a "feeling" as a guide is fine when we are honest about it.  In the end, it is not what you believe it is about how we help each other dispite our differences.