We've been discussing this for a while. :D I don't really go into detail all that often, and that's not gonna change, but I was one of these "spiritual atheist's" through all of my teenage years and I didn't completely shake it until I was about twenty-one (four years ago). I did not believe in god concepts, of course, during all of this, but I did entertain afterlife concepts until I was about eighteen and began studying a bit of philosophy in college. (When I realized that afterlife concepts were purely pessimistic.) Even THEN for a few more years I studied the occult (as I had for years) and saw no conflict between my atheism and it. Looking back now... I don't see how I didn't. Anyway, I just wanted to post a few links to some occultist material for all of your study and amusement. These are the things that I, as a spiritual atheist, prescribed to. Specifically, I studied the painter/occultist Austin Osman Spare (and I still do have a profound interest in the man, but that's cause I love characters from history and he was quite character).
Should I have scoffed at all of this? Maybe. I did gain a lot of meditation techniques and the like that work great after I spend a hard day running cat-5 in buildings, though. And if I hadn't delved deeply into such things then I don't know that I would be the strong atheist I am today.
He is what I would term a spiritual atheist. For the few years he and I had regular contact I never once heard him say anything that made me think he was anything other than an atheist who prescribed to 'woo' and lots of it. :D
I believe there is a legitimate area of inquiry as to the obviously misinterpreted phenomena that causes people to buy into woo woo wholesale and with little queston. It seems that there may be something going on - either solely in a huge number of people's minds - or in reality - that is not well understood.
It is very tempting to simply dismiss it as 'mass delusion.' Well, that's a pretty non-specific answer to an empirically provable situation - a dangerous one at that. If we could understand why people so readily and profoundly buy into what - to us - is so obviously nonsense, we might have a better shot at snapping them out of it. Or not. But I think it behooves us to explore this.
In the process, I think many atheists are willing to re-examine phenomena that we actually don't fully understand with a less anthropocentric or solipsistic eye than many other atheists are willing to. In the process, terms, such as 'spirituality' are attempted to be used for the phenomena, but within the context of an entirely different take on it.
Calling something that is ubiquitous and, potentially dangerous such as religious faith - woo woo - and leaving it at that isn't helpful. Using logic to try and dislodge faith has been found to be insufficient to the task. But if we could show the proverbial blind men that they weren't touching a rope, a wall, a hose, etc. but an elephant instead - maybe more of them would have an aha moment.
So - I find it can take a second to sort out who is simply willing to inquire from those who simply cannot let go of their woo.
In the meantime, I have found it more problematic to use the term 'spirituality' in reference to this inquiry than not. So I have stopped.
The answer is obvious: atheists refer to "spirituality" not in the religious sense of a supernatural spirit or soul, but in the sense of how one is uplifted with awe and wonder when contemplating this magnificent universe and our small part of it.
You cannot separate it from its defined intent; it invokes the First Cause to use the words "spirit", "spiritual" or "spirituality" ... all metaphysical, regardless an individuals intent to rationalise it as otherwise.
Atheist spirituality is not an oxymoron. It makes perfect sense.
The word atheist itself means "without god". It does not mean "without religion or superstition". When you label yourself an atheist, you are simply stating that you don't believe in god, not that you also lack belief in any other supernatural beliefs.
By definition, buddhists are also atheists. They do not believe in a god, however they are highly spiritual. Buddhism is an atheistic religion. Those that are part of the Christian faith partake in a theistic religion, meaning they do believe in a god.
Hence whenever someone asks me what I "am" (religion-wise), I never say atheist. I say I'm devoid of any religion, and I do not adhere to any group. I don't want to be grouped in with people that think likewise, I just want to be myself.