{Should I admit that I don't really understand the Angel quote? It never made sense to me. I don't want to be shunned. Like I said, moral philosophy is hard}
Here's the whole quote: "If there's no great glorious end to all this, if nothing we do matters...then all that matters is what we do. 'Cause that's all there is. What we do. Now. Today."
Which I took as, if there's no heaven/afterlife, then what we do isn't going to affect whether we end up in heaven or hell. And since all we have is right now, what we do matters, because it affects our here and now.