Sukisho beat me to the punch...but then, she's the one that showed me that a couple days ago.

That said, I do not consider atheism to be spiritually or morally devoid -- I think that argument is often employed by people trying to put it down. It means having to justify one's own existence in some other way besides a religious reckoning. 

Beyond that, while someone might note that a practice is derived from a previous religious practice, odds are that religious practice evolved from a very different belief and it just goes on with a repeat of the cycle. (Usually, in such an argument -- I do my trolling and fighting off the Guild if you must know -- you just have to show that it evolved from a different religion and it's over -- guy goes ballistic or silent :newlol) We've been writing on this rock for thousands of years, and people have been borrowing ideas from each other from the getgo. I think it's best to tacitly agree that this is the case with religious vs. secular law and moralities and it avoids the embarrassment of having a bad position get refuted by example. As a guy with a degree in history, I can generally reach back further in a tit for tat argument about the chicken or the egg, but I don't see the point -- I sort of feel like it's like spinning the hamster wheel. It's a fun exercise, but it doesn't get much done.

Religion's inherent redeeming values vs. the inherent redeeming values of atheism or agnosticism? I'm not sure these exist. I tend to look at it through the individual end user. Mother Theresa made her religion a redeeming and uplifting thing that justified a life spent in what amounts to a state of grace. Others have used it for darker purposes. By the same token, you have figures that have rebelled against the dictates and strictures of religion to our great benefit and others that have used atheism as a justification for purges. 

I have a hard time simplifying it to, 'this belief is good' and/or 'this belief system is bad' when we're talking about something like Christianity or Islam or Judaism...and even when an entire sect seems to be rotten apples entirely, I tend to consider it a phenomenon of violent rhetoric and a misanthropic philosophy validating the impulses of people that don't function in normal society -- I hold the same view for white supremacists. I look at human nature in askance, not the specific beliefs.