When I was a young JW i saw and walked up the mountains of our locality and had a huge sense of awe and a tinge of sadness on my first visit, I remember, it was half way up, looking down to a body of water. I couldn't nail why, but I put these feelings down to 'spiritual' experiences.
I felt at one with life itself, but somewhat melancholic at the end of the emotional rush.
I remember daydreaming on a sunday in the middle of a watchtower 20+ years ago, I remember where I was sat, the winter sunlight coming in to the k.h. via the tinted glass. I was pondering the field of atoms, us being made of atoms as was the universe. I attempted to picture the universe from an atomic level and I saw that the universe would simply be one dense field of atoms.... No people, animals, planets... My mind blew a fuse at that point and i got lost in the same sense of awe once more but with that same tinge of sadness at its dissipation. This same experience happened a few times in my youth. Each time felt like I was plugging into the universe for a millisecond, having its truths downloaded and them existing as quickly as they dissapeared in my mind, that typical description of feeling 'at one with the universe.'
I remember talking to my group overseer about it, he seemed a smart guy and to my amazement he said he knew the sense I was talking of. He was a naturalist too, he left the Jw's in the end, with his son, leaving his wife behind. I respect the man deeply to this day yet have not had the means to talk to him. Anyway, I asked him if the feeling was based on a spiritual connection tarnished with our imperfection, explaining the awe and the sadness. He didn't seem convinced and when I examined myself further i knew those feelings were more than that, they were a profound recognition or something but of what I wasn't sure.
When I distanced myself from the Jw's many years later those feelings had long stopped, i started my education in science once more at age 26 and amazingly those feelings returned. Whenever examining something universal or dimensionally huge or even infinitely small . I would get lost in thought, then awe and wonder, then the wave of sadness hit me... and on one of those occasions some 2 years later, now an atheist, for the first time ever I understood it.
It was like an explosion when I recognised it. The awe was always a recognition of the fragility of me, before a mountain, before a universe, before an atomic world..... The sadness was my acceptance that I unlike the mountain and universe will die, will not be around to understand it or see it other than my time now. What makes life and the universe so awe inspiring is also what makes it a little sad, it is a privelage we have for a limited time. As soon as these thoughts crossed my neurones I knew for sure that was my feeling explained exactly, from all those years ago and it continues today,
When i see something profound, whether it be old, big, small or complex, I know it was here long before me and will be here long after me,,,, a beautiful and yet melancholic realisation.
What i was calling spiritual, i now know to be very human and I am more appreciative of it than ever, for as an atheist, my life is more precious to me, which makes the value and desire to live even stronger and the search for awe in the universe more exciting than ever before.
it is just my anecdotal story and just as other people's experiences are just their own, this is just mine.
But that is my experience of feeling awe, wonder snd spiritual and it's place in my life. I have discussed this a few times here, I have read other people reach the same conclusion too. Oddly I once read it mid fictional book as a charachter expressed the same sense (Alex Garland).
One thing is for sure, theists or one religion or one god or one belief system don't own awe, wonder, spirituality or such experiences And I am lost to know how you would know there are atheists too afraid to say them, as by that explination they would not tell you or if did were obviously content to do so. Weird.