What IS good, and how do we determine it?

[Whateverist]

I determine good by way of how it makes me feel.  

If someone treats me kindly and respectfully, I am going to understand the good and reciprocate it.  No god needed.

If someone does something that hurts me, obviously that is not good.

Thank Kitan.

But don't you believe there are some things that ARE immoral regardless of how someone might "feel?"

For example, a jealous husband can feel that murdering his cheating wife is not immoral. But he is wrong. It IS immoral regardless of how he feels or what he thinks. The question is, where does the universal truth "murder is wrong" come from?

A jealous husband doesn't think enough if he murders his faithless wife.  The pull of morality has a limited effect.  In the example you raise, the pull of morality was insufficient.  That would be as true if the jealous husband was a devout Catholic as it would be if he were an atheist.  Subscribing to a system of morality, Catholic or otherwise, doesn't make one immune to the feeling and emotions we are all subject to.  Fortunately many of us, Catholic and otherwise, manage not to violate our higher values even in the grip of strong emotion.